EASY Volume of shapes
posted by Jay on .
The right triangular prism has bases that are equilateral triangles. The height is 8 in and the side of the base is 5 in , what is the prism's volume?

area = area of base x heigh
so the hard part is to find the area of the equilateral triangle with sides 5
1. easiest way:
area = (1/2) side^2 x sin60 = (1/2)(25)*√3/2
= 25√3
2. draw in the height of the triangle, call it h
h/5 = sin60
h = 5sin60
area = (1/2)(base x height)
= (1/2)(5)(5√3/2) = 25√3
(same as abov)
volume of prism = 25√3(8) = 200√3 cubic inches 
thanks for the help