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human
Two points $A(x_1, y_1)$ and $B(x_2, y_2)$ are chosen on the graph of $f(x) = \ln x$, with $0 < x_1 < x_2$. The points $C$ and $D$ trisect $\overline{AB}$, with $AC < CB$. Through $C$ a horizontal line is drawn to cut the curve at $E(x_3, y_3)$. Find $x_3$ if $x_1 = 1$ and $x_2 = 1000$.
gpt
Since $C$ is the trisector of line segment $\overline{AB}$ closer to $A$, the $y$-coordinate of $C$ is equal to two thirds the $y$-coordinate of $A$ plus one third the $y$-coordinate of $B$. Thus, point $C$ has coordinates $(x_0, \frac{2}{3} \ln 1 + \frac{1}{3}\ln 1000) = (x_0, \ln 10)$ for some $x_0$. Then the horizon...
human
Five identical rectangles are arranged to form a larger rectangle $PQRS$, as shown. The area of $PQRS$ is $4000$. What is the length, $x$, rounded off to the nearest integer? [asy] real x = 1; real w = 2/3; // Draw outer square and labels pair s = (0, 0); pair r = (2 * x, 0); pair q = (3 * w, x + w); pair p = (0, x ...
gpt
Let $w$ be the width of each of the identical rectangles. Since $PQ=3w$, $RS=2x$ and $PQ=RS$ (because $PQRS$ is a rectangle), then $2x = 3w$, or $$w=\frac{2}{3}x.$$ Therefore, the area of each of the five identical rectangles is $$x\left(\frac{2}{3}x\right)=\frac{2}{3}x^2.$$ Since the area of $PQRS$ is 4000 and it is m...
human
Compute $\cos 150^\circ$.
gpt
Let $P$ be the point on the unit circle that is $150^\circ$ counterclockwise from $(1,0)$, and let $D$ be the foot of the altitude from $P$ to the $x$-axis, as shown below. [asy] pair A,C,P,O,D; draw((0,-1.2)--(0,1.2),p=black+1.2bp,Arrows(0.15cm)); draw((-1.2,0)--(1.2,0),p=black+1.2bp,Arrows(0.15cm)); A = (1,0); O= (0...
human
What is the area, in square units, of the interior region formed by the lines $y = 2x - 4, y = -3x +16$ and the $y$-axis?
gpt
To find the vertices of the triangle, we find where the two lines $y=2x-4$ and $y=-3x+16$ intersect. Solving $2x-4=-3x+16$, we get $x=4$. Substituting $x=4$ back into $y=2x-4$, we find $y=4$. Therefore, $(4,4)$ is one of the vertices of the triangle. The other two vertices are the $y$-intercepts of the two lines, na...
human
A circular sheet of paper with radius of $6$ cm is cut into three congruent sectors. What is the height of the cone in centimeters that can be created by rolling one of the sections until the edges meet? Express your answer in simplest radical form.
gpt
The circumference of the whole circle is $2 \pi \cdot 6 = 12 \pi$, so the circumference of the base of the cone is $12 \pi/3 = 4 \pi$. Hence, the radius of the base of the cone is $4 \pi/(2 \pi) = 2$. [asy] unitsize(2 cm); fill((0,0)--arc((0,0),1,-60,60)--cycle,gray(0.7)); draw(Circle((0,0),1)); draw((0,0)--dir(60))...
human
What is the ratio of the volume of cone $A$ to the volume of cone $B$? Express your answer as a common fraction. [asy] size(260); draw(ellipse((0,0),14.8,6),S); label("Cone $A$", (0,-6), S); draw((0,28.3)--(0,0),dashed); label("$28.3$",(0,14),SW); draw((-14.8,0)--(0,28.3)--(14.8,0)); draw("$14.8$",(-14.8,0)--(0,0),N,da...
gpt
Let $x = 14.8$ and $y = 28.3$. Then the volume of cone $A$ is \[\frac{1}{3} \pi x^2 y,\] and the volume of cone $B$ is \[\frac{1}{3} \pi y^2 x,\] so the desired ratio is \[\frac{\frac{1}{3} \pi x^2 y}{\frac{1}{3} \pi xy^2} = \frac{x}{y} = \frac{14.8}{28.3} = \boxed{\frac{148}{283}}.\]
human
Two sides of an isosceles triangle are 10 inches and 20 inches. If the shortest side of a similar triangle is 50 inches, what is the perimeter of the larger triangle?
gpt
First of all, the third side of the smaller triangle cannot be 10 inches because sides of 10, 10 and 20 inches would not form a triangle. The smaller triangle must have sides of 10, 20 and 20 inches. If the shortest side of the similar triangle is 50 inches, then the other two sides are 100 inches and 100 inches. Thus,...
human
What is the slope of the line that is tangent to a circle at point (5,5) if the center of the circle is (3,2)? Express your answer as a common fraction.
gpt
If a line can be drawn tangent to a circle a the point $(5,5)$, then it must be possible to draw a radius from the center of the circle to the point $(5,5)$. This radius will have a slope of: $$\frac{5-2}{5-3}=\frac{3}{2}$$ A key fact to remember is that tangents to a circle at a certain point are perpendicular to rad...
human
In $\triangle ABC,$ $AB=AC=25$ and $BC=23.$ Points $D,E,$ and $F$ are on sides $\overline{AB},$ $\overline{BC},$ and $\overline{AC},$ respectively, such that $\overline{DE}$ and $\overline{EF}$ are parallel to $\overline{AC}$ and $\overline{AB},$ respectively. What is the perimeter of parallelogram $ADEF$? [asy] real...
gpt
Since $\overline{DE} \parallel \overline{AC}$ and $\overline{EF} \parallel \overline{AB},$ triangles $\triangle BDE$ and $\triangle EFC$ are similar to $\triangle ABC$, and so they are also isosceles. That is, $BD = DE$ and $EF = FC.$ Then the perimeter of $ADEF$ is \[\begin{aligned} AD + DE + EF + AF &= AD + BD + FC ...
human
In triangle $BCD$, $\angle C = 90^\circ$, $CD = 3$, and $BD = \sqrt{13}$. What is $\tan B$?
gpt
[asy] pair B,C,D; B = (0,0); C = (2,0); D = (2,-3); draw(B--C--D--B); draw(rightanglemark(B,C,D,7)); label("$D$",D,SE); label("$B$",B,NW); label("$C$",C,NE); label("$3$",(C+D)/2,E); label("$\sqrt{13}$",(B+D)/2,SW); [/asy] Because $\triangle BCD$ is a right triangle, we know that $\tan B = \frac{CD}{BC}$. By the Pytha...
human
In the circle with center $O$, the measure of $\angle RIP$ is $36^\circ$ and $OR=10$ cm. Find the number of centimeters in the length of arc $RP$. Express your answer in terms of $\pi$. [asy] draw((1,0)..(0,1)..(-1,0)..(0,-1)..cycle); draw((0,0)--(4/5,3/5)--(-1,0)--(4/5,-3/5)--cycle); label("$O$",(0,0),W); label("$I$",...
gpt
Since $\angle RIP$ is inscribed in arc $RP$, the measure of arc $RP$ is $2\angle RIP = 72^\circ$. Therefore, arc $RP$ is $\frac{72}{360} =\frac15$ of the circumference of the whole circle. The circle's circumference is $2OR\pi = 20\pi$ cm, so the length of arc $RP$ is $\frac15\cdot 20\pi = \boxed{4\pi}$ cm.
human
In $\Delta ABC$, $AC = BC$, $m\angle DCB = 40^{\circ}$, and $CD \parallel AB$. What is the number of degrees in $m\angle ECD$? [asy] pair A,B,C,D,E; B = dir(-40); A = dir(-140); D = (.5,0); E = .4 * dir(40); draw(C--B--A--E,EndArrow); draw(C--D,EndArrow); label("$A$",A,W); label("$C$",C,NW);label("$B$",B,E);label("$D$...
gpt
Angles $\angle DCB$ and $\angle B$ are alternate interior angles, so they are congruent. Therefore, $m\angle B=40^\circ$. Since $AC=BC$, triangle $\triangle ABC$ is isosceles with equal angles at $A$ and $B$. Therefore, $m\angle A=40^\circ$. Finally, $\angle A$ and $\angle ECD$ are corresponding angles, so $m\angle E...
human
In the diagram, four circles of radius 4 units intersect at the origin. What is the number of square units in the area of the shaded region? Express your answer in terms of $\pi$. [asy] import olympiad; import geometry; size(100); defaultpen(linewidth(0.8)); fill(Arc((1,0),1,90,180)--Arc((0,1),1,270,360)--cycle,gray(0....
gpt
The shaded region consists of 8 copies of the checkered region in the figure below. The area of this region is the difference between the area of a quarter-circle and the area of an isosceles right triangle. The area of the quarter-circle is $\frac{1}{4}\pi (4)^2=4\pi$ square units, and the area of the isosceles righ...
human
What is the height of Jack's house, in feet, if the house casts a shadow 56 feet long at the same time a 21-foot tree casts a shadow that is 24 feet long? Express your answer to the nearest whole number.
gpt
The ratio of shadow lengths is $\frac{56}{24}=\frac{7}{3}$. This is the same as the ratio of actual heights, so if $h$ is the height of the house, $$\frac{h}{21}=\frac{7}{3}\Rightarrow h=\boxed{49}$$
human
One angle of a parallelogram is 120 degrees, and two consecutive sides have lengths of 8 inches and 15 inches. What is the area of the parallelogram? Express your answer in simplest radical form.
gpt
[asy] pair A,B,C,D,X; A = (0,0); B= (15,0); D = rotate(60)*(8,0); C = B+D; X = (4,0); draw(X--A--D--C--B--X--D); label("$A$",A,SW); label("$D$",D,NW); label("$C$",C,NE); label("$B$",B,SE); label("$X$",X,S); [/asy] If one angle of the parallelogram is 120 degrees, then another angle between adjacent sides has measure $...
human
A pipe with inside diameter 10'' is to carry water from a reservoir to a small town in an arid land. Neglecting the friction and turbulence of the water against the inside of the pipes, what is the minimum number of 2''-inside-diameter pipes of the same length needed to carry the same volume of water to the arid town?
gpt
Let the length of the pipes be $h$. The volume of the 10-inch pipe is $\pi (5^2) (h) = 25\pi h$ cubic inches and the volume of each 2-inch pipe is $\pi (1^2)(h) = \pi h$ cubic inches. Hence we see it takes exactly 25 2-inch pipes to match the volume of one 10-inch pipe. The answer is $\boxed{25}$ pipes.
human
A circle with a radius of 2 units has its center at $(0, 0)$. A circle with a radius of 7 units has its center at $(15, 0)$. A line tangent to both circles intersects the $x$-axis at $(x, 0)$ to the right of the origin. What is the value of $x$? Express your answer as a common fraction.
gpt
To begin, we can draw a diagram as shown: [asy] size(150); draw((0,8)--(0,-8),linewidth(.5)); draw((-4,0)--(23,0),linewidth(.5)); draw(Circle((0,0),2),linewidth(.7)); draw(Circle((15,0),7),linewidth(.7)); draw((-2,-4)--(14,8),linewidth(.7)); draw((0,0)--(1.3,-1.5),linewidth(.7)); draw((15,0)--(10.7,5.5),linewidth(.7));...
human
What is the radius of the circle inscribed in triangle $ABC$ if $AB = AC=7$ and $BC=6$? Express your answer in simplest radical form.
gpt
Let $r$ be the radius of the inscribed circle. Let $s$ be the semiperimeter of the triangle, that is, $s=\frac{AB+AC+BC}{2}=10$. Let $K$ denote the area of $\triangle ABC$. Heron's formula tells us that \begin{align*} K &= \sqrt{s(s-AB)(s-AC)(s-BC)} \\ &= \sqrt{10\cdot 3\cdot 3\cdot 4} \\ &= 6\sqrt{10}. \end{align*} ...
human
In $\triangle ABC$, point $D$ is the midpoint of side $BC$. Point $E$ is on $AC$ such that $AE:EC =1:2$. Point $F$ is on $AD$ such that $AF:FD=3:1$. If the area of $\triangle DEF$ is 17, determine the area of $\triangle ABC$. [asy] size(6cm);defaultpen(fontsize(11)); pair b =(0,0);pair c = (10, 0);pair a=(4, 6); pair...
gpt
We will also adopt the notation $|\triangle XYZ|$ to represent the area of $\triangle XYZ$. Recall that if two triangles have their bases along the same straight line and they share a common vertex that is not on this line, then the ratio of their areas is equal to the ratio of the lengths of their bases. Using this ...
human
A circle is circumscribed about an equilateral triangle with side lengths of $9$ units each. What is the area of the circle, in square units? Express your answer in terms of $\pi$.
gpt
[asy] size(100); defaultpen(linewidth(.8)); draw((0,0)--(4.5,7.794)--(9,0)--cycle); draw(Circle((4.5,2.598),5.196)); draw((4.5,7.794)--(4.5,0)); dot((4.5,2.598)); label("$O$",(4.5,2.598),W); label("$A$",(4.5,7.794),N); label("$B$",(9,0),E); label("$M$",(4.5,0),S); [/asy] Above is the diagram implied by the problem, wi...
human
$ABCDEFGH$ shown below is a cube with volume 1. Find the volume of pyramid $ABCH$. [asy] import three; triple A,B,C,D,EE,F,G,H; A = (0,0,0); B = (1,0,0); C = (1,1,0); D= (0,1,0); EE = (0,0,1); F = B+EE; G = C + EE; H = D + EE; draw(B--C--D); draw(B--A--D,dashed); draw(EE--F--G--H--EE); draw(A--EE,dashed); draw(B--F);...
gpt
We add the edges of the pyramid to our diagram below. [asy] import three; triple A,B,C,D,EE,F,G,H; A = (0,0,0); B = (1,0,0); C = (1,1,0); D= (0,1,0); EE = (0,0,1); F = B+EE; G = C + EE; H = D + EE; draw(B--C--D); draw(B--A--D,dashed); draw(EE--F--G--H--EE); draw(B--H--A--EE,dashed); draw(A--C,dashed); draw(B--F); draw...
human
Parallelogram $ABCD$ with $A(2,5)$, $B(4,9)$, $C(6,5)$, and $D(4,1)$ is reflected across the $x$-axis to $A'B'C'D'$ and then $A'B'C'D'$ is reflected across the line $y=x+1$ to $A''B''C''D''$. This is done such that $D'$ is the image of $D$, and $D''$ is the image of $D'$. What is the ordered pair of $D''$ in the coordi...
gpt
Reflecting a point across the $x$-axis multiplies its $y$-coordinate by $-1$. Therefore, $D'=(4,-1)$. To reflect $D'$ across the line $y=x+1$, we first translate both the line and the point down one unit so that the equation of the translated line is $y=x$ and the coordinates of the translated point are $(4,-2)$. To...
human
The diagonals of a regular hexagon have two possible lengths. What is the ratio of the shorter length to the longer length? Express your answer as a common fraction in simplest radical form.
gpt
The two possible diagonal lengths are $AB$ and $AC$. The measure of an interior angle of a regular hexagon is $180(6-2)/6=120$ degrees. Therefore, angle $BCA$ measures $120/2=60$ degrees. Also, the base angles of the isosceles triangle with the marked 120-degree angle each measure $(180-120)/2=30$ degrees. This impli...
human
Given that the diagonals of a rhombus are always perpendicular bisectors of each other, what is the area of a rhombus with side length $\sqrt{89}$ units and diagonals that differ by 6 units?
gpt
Because the diagonals of a rhombus are perpendicular bisectors of each other, they divide the rhombus into four congruent right triangles. Let $x$ be half of the length of the shorter diagonal of the rhombus. Then $x+3$ is half of the length of the longer diagonal. Also, $x$ and $x+3$ are the lengths of the legs of ...
human
The sides of a triangle have lengths $11, 15,$ and $k,$ where $k$ is a positive integer. For how many values of $k$ is the triangle obtuse?
gpt
The longest side of the triangle either has length $15$ or has length $k.$ Take cases: If the longest side has length $15,$ then $k \le 15.$ The triangle must be nondegenerate, which happens if and only if $15 < 11 + k,$ or $4 < k,$ by the triangle inequality. Now, for the triangle to be obtuse, we must have $15^2 > 1...
human
In the figure, circle $O$ has radius 6 units. Chord $CD$ has length 8 units and is parallel to segment $KB$. If $KA$ = 12 units and points $K$, $A$, $O$ and $B$ are collinear, what is the area of triangle $KDC$? Express your answer in simplest radical form. [asy] draw(Circle((0,0),6)); dot((0,0)); label("$O$",(0,0),S);...
gpt
The center of the circle, $O$, is the midpoint of the chord $AB$ (the diameter of the circle). Since we are told that $CD$ is parallel to $AB$, if we draw a line that is perpendicular to $AB$, it will be perpendicular to $CD$ as well. Now let's draw a segment from $O$ to the midpoint of the chord $CD$, which we will ca...
human
Inside a square with side length 10, two congruent equilateral triangles are drawn such that they share one side and each has one vertex on a vertex of the square. What is the side length of the largest square that can be inscribed in the space inside the square and outside of the triangles? [asy] size(100); pair A, ...
gpt
The largest possible square is the square with one vertex on the triangles' coincident vertices and with sides parallel to and coincident with those of the big square. There are two of them. We draw them in and label the diagram as shown: [asy] size(150); pair A, B, C, D, E, F; B=(0,0); A=(0,10); D=(10,10); C=(10,0);...
human
Charlyn walks completely around the boundary of a square whose sides are each 5 km long. From any point on her path she can see exactly 1 km horizontally in all directions. What is the area of the region consisting of all points Charlyn can see during her walk, expressed in square kilometers and rounded to the nearest ...
gpt
At any point on Charlyn's walk, she can see all the points inside a circle of radius 1 km. The portion of the viewable region inside the square consists of the interior of the square except for a smaller square with side length 3 km. This portion of the viewable region has area $(25-9)$ km$^2$. The portion of the viewa...
human
In the figure, $\angle EAB$ and $\angle ABC$ are right angles, $AB=4,$ $BC=6,$ $AE=8,$ and $\overline{AC}$ and $\overline{BE}$ intersect at $D.$ What is the difference between the areas of $\triangle ADE$ and $\triangle BDC?$ [asy] pair A,B,C,D,I; I=(0,8); A=(0,0); B=(4,0); C=(4,6); D=(2.5,4); draw(A--B--I--cycle,linew...
gpt
Let $x,$ $y,$ and $z$ be the areas of $\triangle ADE,$ $\triangle BDC,$ and $\triangle ABD,$ respectively. The area of $\triangle ABE$ is \[\frac 1 2\cdot 4\cdot 8= 16= x+z,\]and the area of $\triangle BAC$ is \[\frac 1 2\cdot 4\cdot 6 = 12= y+z.\]Subtracting these equations gives $$(x+z) - (y+z) = 16-12\implies x - y ...
human
The convex pentagon $ABCDE$ has $\angle A = \angle B = 120^\circ$, $EA = AB = BC = 2$ and $CD = DE = 4$. What is the area of $ABCDE$? [asy] unitsize(1 cm); pair A, B, C, D, E; A = (0,0); B = (1,0); C = B + dir(60); D = C + 2*dir(120); E = dir(120); draw(A--B--C--D--E--cycle); label("$A$", A, SW); label("$B$...
gpt
We can divide the pentagon into 7 equilateral triangles of side length 2. [asy] unitsize(1 cm); pair A, B, C, D, E; A = (0,0); B = (1,0); C = B + dir(60); D = C + 2*dir(120); E = dir(120); draw(A--B--C--D--E--cycle); draw(C--E); draw((C + D)/2--(D + E)/2); draw(A--(C + D)/2); draw(B--(D + E)/2); label("$A$", A, SW...
human
An equilateral triangle has an area of $64\sqrt{3}$ $\text{cm}^2$. If each side of the triangle is decreased by 4 cm, by how many square centimeters is the area decreased?
gpt
We first consider an equilateral triangle with side length $s$. If we construct an altitude, it will divide the equilateral triangle into two congruent $30-60-90$ triangles with the longest side having length $s$ and the altitude opposite the $60^\circ$ angle. Since the side lengths of a $30-60-90$ triangle are in a $1...
human
A cube has edges of length 1 cm and has a dot marked in the centre of the top face. The cube is sitting on a flat table. The cube is rolled, without lifting or slipping, in one direction so that at least two of its vertices are always touching the table. The cube is rolled until the dot is again on the top face. Th...
gpt
Suppose the cube rolls first over edge $AB$. Consider the cube as being made up of two half-cubes (each of dimensions $1 \times 1 \times \frac{1}{2}$) glued together at square $PQMN$. (Note that $PQMN$ lies on a vertical plane.) Since dot $D$ is in the centre of the top face, then $D$ lies on square $PQMN$. [asy] //...
human
The points $(1, 7), (13, 16)$ and $(5, k)$, where $k$ is an integer, are vertices of a triangle. What is the sum of the values of $k$ for which the area of the triangle is a minimum?
gpt
We begin by finding the equation of the line $\ell$ containing $(1,7)$ and $(13,16)$. The slope of $\ell$ is $\frac{16-7}{13-1} = \frac{9}{12} = \frac 34$, so the line has the point-slope form $y - 7 = \frac 34 (x - 1)$. Substituting the value $x = 5$, we obtain that $y = 7 + \frac 34 (5-1) = 10$. It follows that the p...
human
A line with slope of $-2$ intersects the positive $x$-axis at $A$ and the positive $y$-axis at $B$. A second line intersects the $x$-axis at $C(8,0)$ and the $y$-axis at $D$. The lines intersect at $E(4,4)$. What is the area of the shaded quadrilateral $OBEC$? [asy] draw((0,-1)--(0,13)); draw((-1,0)--(10,0)); fill((0,...
gpt
First, we can create a square with the points $O$ and $E$ as opposite corners. Label the other two points as $X$ and $Y$ with $X$ on $OC$ and $Y$ on $OB$. We get that $X$ is $(4,0)$ and $Y$ is $(0,4)$. We can find the area of the figure by finding the area of the square and the two triangles created. The area of the ...
human
In triangle $ABC$, $AB = 3$, $BC = 4$, $AC = 5$, and $BD$ is the angle bisector from vertex $B$. If $BD = k \sqrt{2}$, then find $k$.
gpt
By Pythagoras, $\angle ABC = 90^\circ$. Let $P$ and $Q$ be the projections of $D$ onto $BC$ and $AB$, respectively. [asy] unitsize(1 cm); pair A, B, C, D, P, Q; A = (0,3); B = (0,0); C = (4,0); D = (12/7,12/7); P = (12/7,0); Q = (0,12/7); draw(A--B--C--cycle); draw(B--D); draw(P--D--Q); label("$A$", A, NW); label...
human
In the diagram, $RSP$ is a straight line and $\angle QSP = 80^\circ$. What is the measure of $\angle PQR$, in degrees? [asy] draw((.48,-.05)--(.48,.05)); draw((.52,-.05)--(.52,.05)); draw((1.48,-.05)--(1.48,.05)); draw((1.52,-.05)--(1.52,.05)); draw((1.04,.51)--(1.14,.49)); draw((1.03,.47)--(1.13,.45)); draw((0,0)--...
gpt
Since $RSP$ is a straight line, we have $\angle RSQ+\angle QSP = 180^\circ$, so $\angle RSQ=180^\circ - 80^\circ = 100^\circ$. $\triangle RSQ$ is isosceles with $RS=SQ$, so \[ \angle RQS = \frac{1}{2}(180^\circ - \angle RSQ) = \frac{1}{2}(180^\circ - 100^\circ)=40^\circ . \]Similarly, since $\triangle PSQ$ is isosceles...
human
A wooden model of a square pyramid has a base edge of 12 cm and an altitude of 8 cm. A cut is made parallel to the base of the pyramid that separates it into two pieces: a smaller pyramid and a frustum. Each base edge of the smaller pyramid is 6 cm and its altitude is 4 cm. How many cubic centimeters are in the volume ...
gpt
The piece that is removed from the original pyramid to create the frustum is itself a square pyramid that is similar to the original pyramid. The ratio of corresponding side lengths is 1/2, so the piece that was removed has volume $(1/2)^3 = 1/8$ of the volume of the original pyramid. Therefore, the remaining frustum...
human
Points $(1,-5)$ and $(11,7)$ are the opposite vertices of a parallelogram. What are the coordinates of the point where the diagonals of the parallelogram intersect?
gpt
The diagonals of a parallelogram intersect at the midpoint of each diagonal. So, we simply find the midpoint of $(1,-5)$ and $(11,7)$, which is $\left(\frac{1+11}{2}, \frac{-5+7}{2}\right)=\boxed{(6,1)}$.
human
A regular hexagon is inscribed in a circle of radius 2 units. In square units, what is the area of the hexagon? Express your answer in simplest radical form.
gpt
Connect opposite pairs of vertices of the regular hexagon with line segments as shown. Since each angle of a regular hexagon measures 120 degrees, the six triangles produced are equilateral. The diameter of the circle circumscribed around the hexagon is equal to twice the side length of each of the triangles. Theref...
human
The nine points of this grid are equally spaced horizontally and vertically. The distance between two neighboring points is 1 unit. What is the area, in square units, of the region where the two triangles overlap? [asy] size(80); dot((0,0)); dot((0,1));dot((0,2));dot((1,0));dot((1,1));dot((1,2));dot((2,0));dot((2,1)...
gpt
We color one of the triangles blue, and draw three blue segments connecting its points of intersection with the other triangle. [asy] size(80); dot((0,0)); dot((0,1));dot((0,2));dot((1,0));dot((1,1));dot((1,2));dot((2,0));dot((2,1));dot((2,2)); draw((0,0)--(2,1)--(1,2)--cycle, blue+linewidth(0.6)); draw((2,2)--(0,1)...
human
A jar of peanut butter which is 3 inches in diameter and 4 inches high sells for $\$$0.60. At the same rate, what would be the price for a jar that is 6 inches in diameter and 6 inches high?
gpt
The first jar has a volume of $V=\pi r^2h=\pi(\frac{3}{2})^24=9\pi$. The second jar has a volume of $V=\pi r^2h=\pi(\frac{6}{2})^26=54\pi$. Note that the volume of the second jar is 6 times greater than that of the first jar. Because peanut butter is sold by volume, the second jar will be six times more expensive than ...
human
How many integer side lengths are possible to complete a triangle in which the other sides measure 6 units and 3 units?
gpt
By the Triangle Inequality, the unknown side must measure less than $6+3=9$ units. Also, the length of that side plus 3 units must be more than 6 units, so the unknown length must be more than 3 units. There are $\boxed{5}$ possible integer side lengths greater than 3 units and less than 9 units.
human
In the figure, $m\angle A = 28^{\circ}$, $m\angle B = 74^\circ$ and $m\angle C = 26^{\circ}$. If $x$ and $y$ are the measures of the angles in which they are shown, what is the value of $x + y$? [asy] size(150); draw((0,5)--(0,0)--(15,0)--(15,5),linewidth(1)); draw((0,5)--(2,2)--(5,5)--(12,-2)--(15,5),linewidth(.7)); l...
gpt
Starting from the right triangle that contains angle $C$, we can see the third angle in this triangle is $90-26=64$ degrees. By vertical angles, this makes the rightmost angle in the triangle containing angle $y$ also equal to 64 degrees. Thus, the third angle in that triangle has measure $180-(y+64)=116-y$ degrees. ...
human
What is the minimum number of equilateral triangles, of side length 1 unit, needed to cover an equilateral triangle of side length 10 units?
gpt
The ratio of the sides of the small to big equilateral triangle (note that they are similar) is $1/10$, so the ratio of their areas is $(1/10)^2 = 1/100$. So the big equilateral triangle has 100 times the area of a small one, so it will take $\boxed{100}$ small triangles to cover the big one.
human
Circle $B$ has its center at $(-6, 2)$ and a radius of $10$ units. What is the sum of the $y$-coordinates of the two points on circle $B$ that are also on the $y$-axis?
gpt
Note that if the $y$-coordinate of one of the two points is $2+c$, then the $y$-coordinate of the other point must be $2-c$ because the two points must be equidistant from the line $y=2$. Therefore, the sum of the $y$-coordinates of the two points on circle $B$ that are also on the $y$-axis is $\boxed{4}$.
human
Find $\cos C$ in the right triangle shown below. [asy] pair A,B,C; A = (0,0); B = (6,0); C = (0,8); draw(A--B--C--A); draw(rightanglemark(B,A,C,10)); label("$A$",A,SW); label("$B$",B,SE); label("$C$",C,N); label("$10$",(B+C)/2,NE); label("$6$",B/2,S); [/asy]
gpt
The Pythagorean Theorem gives us $AC = \sqrt{BC^2 - AB^2} = \sqrt{100 - 36} = \sqrt{64}=8$, so $\cos C = \frac{AC}{BC} = \frac{8}{10} = \boxed{\frac45}$.
human
A large sphere has a volume of $288\pi$ cubic units. A smaller sphere has a volume which is $12.5\%$ of the volume of the larger sphere. What is the ratio of the radius of the smaller sphere to the radius of the larger sphere? Express your answer as a common fraction.
gpt
We know that the two spheres are similar (in the same sense that triangles are similar) because corresponding parts are in proportion. We will prove that for two spheres that are similar in the ratio $1:k$, their volumes have the ratio $1:k^3$. Let the radius of the first sphere be $r$, so the radius of the other spher...
human
The side lengths of both triangles to the right are given in centimeters. What is the length of segment $AB$? [asy] pair A,B,C,D,E,F,G; A=(0,0); B=12*dir(0); C=20*dir(120); D=8+B; E=D+6*dir(0); F=D+10*dir(120); draw(A--B--C--cycle); draw(D--E--F--cycle); label("A",F,N); label("B",E+(1.4,0)); label("6",.5*(A+B),S); ...
gpt
First, let's label the rest of our vertices. [asy] pair A,B,C,D,E,F,G; A=(0,0); B=12*dir(0); C=20*dir(120); D=10+B; E=D+6*dir(0); F=D+10*dir(120); draw(A--B--C--cycle); draw(D--E--F--cycle); label("A",F,N); label("B",E+(1.4,0)); label("C",D-(2,0)); label("D",C,N); label("E",B+(1.4,0)); label("F",A-(2,0)); label("6",...
human
Triangle $ABC$ with vertices $A(-2, 0)$, $B(1, 4)$ and $C(-3, 2)$ is reflected over the $y$-axis to form triangle $A'B'C'$. What is the length of a segment drawn from $C$ to $C'$?
gpt
Reflecting a point over the $y$-axis negates the $x$-coordinate. So if $C$ is $(-3,2)$, $C'$ will be $(3,2)$. The segment is a horizontal line of length $3+3=\boxed{6}$.
human
Compute $\sin(-60^\circ)$.
gpt
Rotating $60^\circ$ clockwise is the same as rotating $360^\circ - 60^\circ = 300^\circ$ counterclockwise, so $\sin(-60^\circ) = \sin (360^\circ - 60^\circ) = \sin 300^\circ$. Let $P$ be the point on the unit circle that is $300^\circ$ counterclockwise from $(1,0)$, and let $D$ be the foot of the altitude from $P$ to ...