perimeter


Definition of Perimeter

  • Perimeter is the distance around a polygon.

Examples of Perimeter

  • The perimeter of the rectangle shown is AB + BC + CD + DA = 8 + 5 + 8 + 5 = 26 units

  • Perimeter of a rectangle can also be found using the formula 2(l + w), where l is the length and w is the width.

Solved Example on Perimeter

ABC is an equilateral triangle and the perimeter of triangle ABC is 12 in. Find the measure of each side.

Choices:
A. 36 in.
B. 4 in.
C. 12 in.
D. 6 in.
Correct Answer: B
Solution:
Step 1: In triangle ABC, AB = BC = CA
Step 2: Let AB = BC = CA = x in.
Step 3: Perimeter of ΔABC = AB + BC + CA
Step 4: AB + BC + CA = 12
Step 5: x + x + x = 12                    [Substitute AB = BC = CA = x.]
Step 6: 3x = 12                              [Combine like terms.]
Step 7:                                 [Divide each side by 3.]
Step 8: x = 4                                  [Simplify.]
Step 9: AB = BC = CA = 4 in.
Step 10: So, the measure of each side is 4 in.

Related Terms for Perimeter

  • Polygon