Hotmath
Math Homework. Do It Faster, Learn It Better.

Area

The area of a plane figure, measured in square units (or units 2 ), 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 = s 2
s is the length of the side of the square.
Rectangle
A = L W
L and W are the lengths of the rectangle's sides (length and width).
Triangle
A = 1 2 b h
b and h are the base and height .
Triangle
A = s ( s − a ) ( s − b ) ( s − c ) Where     s = a + b + c 2
a , b , and c are the side lengths and s is the semiperimeter
Parallelogram
A = b h
b is the length of the base and h is the height.
Trapezoid
A = b 1 + b 2 2 h
b 1 and b 2 are the lengths of the parallel sides and h the distance (height) between the parallels.
Circle
A = π r 2
r is the radius.