Understand the knowledge points around the perimeter

Perimeter: The integral of the length around the edge of a limited area is called perimeter. The length of the graph is the circumference of the graph. So the perimeter is equal to the sum of all the edges in the graph.

Some commonly used formulas:

Circle: c=πd=2πr (d is the diameter and r is the radius).

Rectangle: c=2(a+b) (a is long and b is wide)

Square: c=4a (a is the side length)

The circumference of a rectangle = (length+width) × 2

The circumference of a square = either side × 4

The perimeter of a triangle = the sum of three sides.

Circumference = diameter × π

Sector circumference: C=2R+nπR÷ 180 (n= central angle)