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Learning Objectives

- Calculate the perimeter of regular and non-regular polygons.

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Perimeter

A **perimeter** is a path that surrounds an area.

The word **perimeter** comes from the Greek *peri* (around) and *meter* (measure).

This means that the **perimeter** is the *measurement around* a shape.

**Perimeter** can be thought of as the length of the outline of a shape. The word may be used either for the path or to describe its length.

To find the **perimeter** of a shape, you need to add up each segment that makes the border of the shape. For instance, in the diagram below, the length of each side of the rectangle is given:

The **perimeter** is the *sum* of all four _____________ of the rectangle, so it would be:

The perimeter of a circle is called **circumference**.

**Reading Check**

1. *Fill in the blank: To find the __________________ of a shape, add up all of its sides.*

2. *Describe* *perimeter* *in your own words:*