Perimeter

Definition of Perimeter

• Perimeter is the distance around a polygon.

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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

                       

Additional Links for Perimeter

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