Perimeter Study Guide

Perimeter is the distance around the outside of a shape. It is the sum of all the side lengths of the shape.

Formulas for Calculating Perimeter

Here are the formulas for calculating the perimeter of different shapes:

• Rectangle: Perimeter = 2 * (length + width)
• Square: Perimeter = 4 * side length
• Triangle: Perimeter = sum of all three sides
• Circle: Perimeter = 2 * π * radius (or π * diameter)

Example Problems

Let's solve some example problems to practice calculating perimeter:

1. Find the perimeter of a rectangle with a length of 8 units and a width of 5 units.

   Perimeter = 2 * (8 + 5) = 2 * 13 = 26 units

2. What is the perimeter of a square with a side length of 10 inches?

   Perimeter = 4 * 10 = 40 inches

3. Determine the perimeter of a triangle with side lengths of 7 cm, 9 cm, and 12 cm.

   Perimeter = 7 + 9 + 12 = 28 cm

4. Calculate the perimeter of a circle with a radius of 5 meters. (Use π ≈ 3.14)

   Perimeter = 2 * 3.14 * 5 = 31.4 meters

Summary

Perimeter is the total distance around the boundary of a shape. To find the perimeter, add up all the side lengths of the shape. Use the appropriate formula for different shapes, such as rectangles, squares, triangles, and circles.