# Area of a Trapezoid

How to find the area of a trapezoid: formula, proof, example, and its solution.

## Formula

*A* = (1/2)(*b*_{1} + *b*_{2})*h**A*: area of a trapezoid*b*_{1}, *b*_{2}: bases*h*: height

## Proof

By a diagonal,

a trapezoid is divided into two triangles.

The areas of the triangles are (1/2)*b*_{1}*h* and (1/2)*b*_{2}*h*.

So *A* = (1/2)*b*_{1}*h* + (1/2)*b*_{2}*h*

= (1/2)(*b*_{1} + *b*_{2})*h*

## Example

*b*_{1} = 5, *b*_{2} = 8, *h* = 4*A* = (1/2)(5 + 8)⋅4