Area

The area of a plane figure, measured in square units(or units2), is the number of squares required to cover it completely.

Example:

The figure shown has an area of 9.5 square units: 8 whole squares plus 3 half-squares.

Here are some formulas for the areas of common plane figures.

Area Formulas
Shape
Formula
Variables
Square

A = s2
s is the length of the side of the square.
Rectangle
 
A = LW
L and W are the lengths of the rectangle's sides (length and width).
Triangle
b and h are the base and height .
Triangle
a, b, and c are the side lengths and s is the semiperimeter
Parallelogram
 
A = bh
b is the length of the base and h is the height.
Trapezoid
b1 and b2 are the lengths of the parallel sides and h the distance (height) between the parallels.
Circle
A = πr2
r is the radius.