Section 2.2: Perimeter

Section 2.2 – Perimeter

The perimeter of a two-dimensional shape is the distance around the shape. You can think of wrapping a string around the 3 sides of a triangle. The length of this string would be the perimeter of the triangle. Or walking around the outside of a park, you walk the distance of the park’s perimeter. Some people find it useful to think “peRIMeter” because the edge of an object is its rim and peRIMeter has the word “rim” in it.

If the shape is a polygon–a closed, two-dimensional shape with straight sides– then you can add up all the lengths of the sides to find the perimeter. Be careful to make sure that all the lengths are measured in the same units. You measure perimeter in linear units, which is one dimensional. Examples of units of measure for length are inches, centimeters, or feet.