Just as there are different sides to every story, there are also different sides to every three-dimensional object. Some questions on the Mathematics Knowledge subtest on the ASVAB will ask you to add up all the sides of a figure to find its total surface area.

Practice questions

  1. Find the surface area:


    A. 48 square yards B. 72 square yards C. 90 square yards D. 96 square yards

  2. Find the surface area:


    A. 2,800 cm2 B. 2,820 cm2 C. 2,826 cm2 D. 2,152 cm2

Answers and explanations

  1. The correct answer is Choice (D).

    The formula to find the surface area of a prism is SA = 2B + Ph, where B represents the area of the base, P represents the perimeter of the base, and h represents the height of the prism.

    First find the area of the triangular base using


    where b represents the triangle's base and h represents its height:


    Find its perimeter by adding the length of each leg:

    6 + 8 + 10 = 24

    The base's area is 24 square yards, the base's perimeter is 24 yards, and the prism's height is 2 yards, so plug that information into the formula for the surface area of a prism:

    SA = 2(24) + 24(2)

    SA = 48 + 48

    SA = 96

    The surface area of the prism is 96 square yards.

  2. The correct answer is Choice (C).

    The formula to find the surface area of a sphere is


    so use the values you know to solve the problem:


About This Article

This article is from the book:

About the book author:

Angie Papple Johnston joined the U.S. Army in 2006 as a Chemical, Biological, Radiological, and Nuclear specialist, ready to tackle chemical weapons in a Level- A HAZMAT suit. She's currently the CBRN noncommissioned officer-in-charge of an aviation battalion in Washington, D.C.

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