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Perimeter of Polygons Study Guide

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Updated on Oct 5, 2011

Practice problems for these concepts can be found at: Perimeter of Polygons Practice Problems

Introduction to Perimeter of Polygons

Lesson Summary

In this lesson, you will learn how to find the distance around convex and concave polygons. You will also learn how to use formulas to find the perimeter of polygons.

Perimeter is found by measuring the distance around an object. Crown molding around a room and a fence around a garden are just two examples of where you might need to find a perimeter. To find the perimeter of an irregular shape, simply add all the lengths of its sides. You can find the perimeters of polygons, which have a uniform shape, by using formulas. Carpenters and landscape architects use perimeters on a regular basis.

Examples:

Find the perimeter of each polygon.
  1. Perimeter of Polygons
  2. Perimeter of Polygons

Solutions:

  1. Perimeter of Polygons
  2. Perimeter of Polygons

Perimeter Formulas

For certain polygons, you can find the perimeter in a more efficient manner. Using a standard formula for a particular shape is faster and easier than adding all the sides. Here are the most commonly used perimeter formulas:

Perimeter of Polygons

Examples:

Use a formula to find each perimeter.

  1. Perimeter of Polygons
  2. Perimeter of Polygons
  3. Perimeter of Polygons

A regular polygon is a polygon with all congruent angles and all congruent sides. So if you know the length of one side of a regular polygon, all you need to do to find its perimeter is multiply the number of sides by the length of a side. In other words, p = ns, where n = number of sides and s = the length of each side.

Working Backward

If you know the perimeter of a polygon, you can also use a perimeter formula to find the length of one of its sides by working backward.

Perimeter of Polygons

Perimeter of Polygons

Perimeter of Polygons

Perimeter of Polygons

Practice problems for these concepts can be found at: Perimeter of Polygons Practice Questions.

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