Stefani slices a right rectangular pyramid with a plane, and the cross-section is in the shape of a trapezoid. How does Stefani slice the pyramid?

A) parallel to the base through the vertex
B) perpendicular to the base through the vertex
C) parallel to the base but not through the vertex
D) perpendicular to the base but not through the vertex

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4

solve systems of equations by graphing. a system of linear equations contains two or more equations e.g. y=0.5x+2 and y=x-2. the solution of such a system is the ordered pair that is a solution to both equations. to solve a system of linear equations graphically we graph both equations in the same coordinate system

(hint): the answer is in the question.