Introduction to Perimeter Word Problems
Learning is not a spectator sport.
—AUTHOR UNKNOWN
This lesson reviews perimeter and the steps to solving word problems involving perimeter.
Perimeter of Figures
The perimeter of a figure is the distance around the outside of the figure. To find the perimeter, add the lengths of each of the sides together to get the total distance around the object.
Find the perimeter of each of the following figures.
Tip:The perimeter of any object is the distance around the object. Instead of memorizing different formulas, just add the sides to find the perimeter of an object. 
Perimeter of Triangles
Every triangle has three sides. To find the perimeter of triangles, add the lengths of the three sides together. If each side is not given, use the clues in the problem to find the measure of the sides.
Example 1
An equilateral triangle has a side of 14 meters. What is the perimeter of the triangle?
Read and understand the question. This question is looking for the perimeter of a triangle.
Make a plan. The perimeter is the distance around the object. Add the lengths of the three sides of the triangle to find the perimeter. Since the triangle is equilateral, each of the three sides is 14 meters.
Carry out the plan. Add the three sides: 14 + 14 + 14 = 42. The perimeter is 42 meters.
Check your answer. To check this solution, start with the perimeter of 42 meters. If each side length is subtracted from this value, the result should be zero: 42 – 14 – 14 – 14 = 0, so this solution is checking.
Example 2
An isosceles triangle has sides 10 meters, 10 meters, and 12 meters. What is the perimeter?
Read and understand the question. This question is looking for the perimeter of the triangle.
Make a plan. The perimeter is the distance around the object. Add the lengths of the three sides of the triangle to find the perimeter. All three side lengths are given.
Carry out the plan. Add the three sides: 10 + 10 + 12 = 32 meters. The perimeter is 32 meters.
Check your answer. To check this solution, start with the perimeter of 32 meters. If each side length is subtracted from this value, the result should be zero: 32 – 10 – 10 – 12 = 0, so this solution is checking.
Perimeter of Rectangles
Each rectangle has four sides and the opposite sides are congruent. Here is an example using the steps to wordproblem solving to find the perimeter of a rectangle.
Example
The length of a rectangle is 24 inches and the width is 13 inches. What is the perimeter?
Read and understand the question. This question is looking for the perimeter of the rectangle.
Make a plan. To find the perimeter, find the distance around the object. Because it is a rectangle, the opposite sides are equal. The four sides are 24 inches, 24 inches, 13 inches, and 13 inches.
Carry out the plan. Add the sides to find the perimeter: 24 + 24 + 13 + 13 = 74. The perimeter is 74 inches.
Check your answer. To check this solution, start with the perimeter of 74 inches. If each side length is subtracted from this value, the result should be zero: 74 – 24 – 24 – 13 – 13 = 0, so this solution is checking.

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