Use formulas to find perimeter of geometric shapes.

Lesson Page Patterns & Functions

Perimeter is the word used to describe the distance around the outside of an object or shape.

You can use a formula to find the perimeter of a square, rectangle, and an equilateral triangle.

Example 1: square
	Find the perimeter of this square using the formula.
Perimeter = side + side + side + side P = s + s + s + s P = 4 x s (formula) Perimeter = 4 x 6 Perimeter = 24 ft. The perimeter is 24 feet.

Example 2: rectangle
	Find the perimeter of the rectangle using the formula.
Perimeter = length + width +length + width Perimeter = 2 x length + 2 x width P = (2 x 8) + (2 x 5) P = 16 + 10 P = 26 ft. The perimeter is 26 feet.

Example 3: Equilateral triangle
	Find the perimeter of the equilateral triangle using the formula.
Perimeter = side + side + side Perimeter = s + s + s P = 3 x s P = 3 x 10 P = 30 in. The perimeter is 30 inches.

Remember: formulas
Square: P = 4 x s
Rectangle : P = 2 x l + 2 x w
Equilateral triangle : P = 3 x s

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