# Formulas for Area of a Triangle

**1.** , where is the base and is the altitude of the triangle.

**2.** Area of an equilateral triangle

, where 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 is given by the formulas