# Areas of circles and sectors

**Formula for the area of a circle**

We can find the area of a circle using the formula:

Area of circle = π*r² *(*r* = radius)

**Finding the area given the diameter**

The formula of an area of a circle given its diameter is:

A = π*d² */ 4

**Finding the area of a sector**

The formula of an area of a sector of a circle is as follows:

Area of a sector AOB =* *π*r²θ*/360