Perimeter and Circumference

Vocabulary

Perimeter- the distance measured around the outside of a geometric figure, measured in units of
length.

Circumference- the distance around a circle

pi- approximately 3.14 or 22
7

Examples

Perimeter

Perimeter is the distance around a two-dimensional shape.

Example 1: the perimeter of this rectangle is 7+3+7+3 = 20

Example 2: the perimeter of this regular pentagon is 3+3+3+3+3 = 5×3 = 15

The perimeter of a circle is called the circumference:

Circumference = 2π × radius

Perimeter Formulas

		Triangle Perimeter = a + b + c
		Square Perimter = 4 × a a = length of side
		Rectangle Perimeter = 2 × (w + h) w = width h = height
		Quadrilateral Perimeter = a + b + c + d
		Circle Circumference = 2πr r = radius
		Sector Perimeter = r(θ+2) r = radius θ = angle in radians
		Ellipse Perimeter = very hard!