# Formulas for Area of a Triangle

1. $A = \frac{1}{2}b \cdot h$, where $b$ is the base and $h$ is the altitude of the triangle.

2. Area of an equilateral triangle

, where $a$ is the length of each side of the triangle.

3. Area of a triangle when two adjacent sides and the included angle is given by

4. Area of a triangle when length of all sides are given

where

5. Area of a triangle with vertices $A\left( {{x_1},{y_1}} \right),\,B\left( {{x_2},{y_2}} \right),\,C\left( {{x_3},{y_3}} \right)$ is given by the formulas