Perimeter

Perimeter is the distance around a two-dimensional shape.

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 × (a + b)
	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!

Try It Yourself