Some questions on the GED Math test will take geometry problems to the next level by combining two-dimensional shapes and asking you to calculate their total perimeter or area.

Practice Questions

Both questions are based on the following image, which shows a rectangle with a semicircular top.


  1. What is the perimeter of the shape?
  2. What is the area of the shape?

Answers and Explanations

  1. The correct answer is C.

    The length of the curved part of the semicircle equals half the circumference of the circle (whose diameter equals 20 mm). The circumference of a full circle is


    so the length is


    The perimeter of the shape consists of this curved length plus the other three sides of the rectangle:


    The correct answer is Choice (C).

  2. The correct answer is B.

    The area of the semicircle is half the area of the full circle (whose diameter equals 20 mm and whose radius equals 10 mm). The area of a full circle is


    The area of the shape consists of the area of the semicircle plus the area of the rectangle:


    Hence, the correct answer is Choice (B).

About This Article

This article is from the book:

About the book author:

Stuart Donnelly, PhD, earned his doctorate in mathe-matics from Oxford University at the age of 25. Since then, he has established successful tutoring services in both Hong Kong and the United States and is considered by leading educators to be one of the most experienced and qualified private tutors in the country.

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