Perimeter

Perimeter is the distance around a two-dimensional shape.

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

Example: 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 Perimeter = 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! An ellipse usually looks like a squashed circle: "F" is a focus, "G" is a focus, and together they are called foci. (pronounced "fo-sigh") The total distance from F to P to G stays the same In other words, we always travel the same distance when going from: point "F" to to any point on the ellipse and then on to point "G"