## Precalculus (6th Edition) Blitzer

If two sides $a$ and $b$ and the included angle $C$ are known in a triangle, then the area of the triangle is found using the formula $\text{Area}=\underline{\frac{1}{2}ab\sin C}$.
$\text{Area}=\frac{1}{2}a\times h$ ……1 Also, $h=b\times \left( \sin C \right)$ ……2 Substituting equation 2 with equation 1, we get $Area=\frac{1}{2}ab\times \left( \sin C \right)$ Hence, we can use this to find the area of the triangle.