Question

Find the surface area of the complex figure. A) 300 feet squared B) 225 feet squared C) 550 feet squared D) 525 feet squared

Answer 1

The correct answer is 550

Answer 2

C) 550 feet squared

Explanation:

Imagine how the surface area of the given figure differs from the surface area of a prism 10 ft by 15 ft by 5 ft without the cutout in the top center. The three 5×5 ft squares that would need to be added to make the prism are of exactly the same area as the three 5×5 ft squares that are the sides and bottom of the cutout.

That is, the area is no different from the area of a 10 ft by 15 ft by 5 ft rectangular prism. That area is ...

A = 2(LW +WH +LH) = 2(10·15 +15·5 + 10·5) ft² = 550 ft²