How do you do a perimeter? - Answers

Example 1:Find the perimeter of a triangle with sides measuring 5 centimeters, 9 centimeters and 11 centimeters.Solution:P = 5 cm + 9 cm + 11 cm = 25 cmExample 2:A rectangle has a length of 8 centimeters and a width of 3 centimeters. Find the perimeter.Solution 1:P = 8 cm + 8cm + 3 cm + 3 cm = 22 cmSolution 2:P = 2(8 cm) + 2(3 cm) = 16 cm + 6 cm = 22 cmIn Example 2, the second solution is more commonly used. In fact, in mathematics, we commonly use the following formula for perimeter of a rectangle:, where is the perimeter, is the length and is the width.In the next few examples, we will find the perimeter of other polygons.Example 3:Find the perimeter of a square with each side measuring 2 inches.Solution:= 2 in + 2 in + 2 in + 2 in = 8 inExample 4:Find the perimeter of an equilateral triangle with each side measuring 4 centimeters.Solution:= 4 cm + 4 cm + 4 cm = 12 cmA square and an equilateral triangle are both examples ofregular polygons. Another method for finding the perimeter of a regular polygon is to multiply the number of sides by the length of one side. Let's revisit Examples 3 and 4 using this second method.Example 3:Find the perimeter of a square with each side measuring 2 inches.Solution:This regular polygon has 4 sides, each with a length of 2 inches. Thus we get:= 4(2 in) = 8 inExample 4:Find the perimeter of an equilateral triangle with each side measuring 4 centimeters.Solution:This regular polygon has 3 sides, each with a length of 4 centimeters. Thus we get:= 3(4 cm) = 12 cmExample 5:Find the perimeter of a regular pentagon with each side measuring 3 inches.Solution:= 5(3 in) = 15 inExample 6:The perimeter of a regular hexagon is 18 centimeters. How long is one side?Solution:= 18 cmLet represent the length of one side. A regular hexagon has 6 sides, so we can divide the perimeter by 6 to get the length of one side ().= 18 cm ÷ 6= 3 cmSummary:To find the perimeter of a polygon, take the sum of the length of each side. The formula for perimeter of a rectangle is: . To find the perimeter of a regular polygon, multiply the number of sides by the length of one side.