Question

The bases of a right prism are isosceles trapezoids with bases of 10 ft and 18 ft

and legs of 5 ft. The height of the prism is 12 ft. Find the surface area in square
feet.

Answer 1

540 ft^2.

Explanation:

The area of the trapezoid = h/2 (10 + 18) = 14h.

By Pythagoras the height h = √(5^2 - 4^2) = 3.

So the area of the 2 trapezoidal bases = 2 * 14*3

= 84 ft^2.

Now we calculate the area of the four lateral rectangular sides:

= 10*12 + 18*12 + 2*5*12

= 456 ft^2.

Total area = 456 + 54

= 540 ft^2.