Precalculus (6th Edition) Blitzer

The area of the triangle is approximately $5\text{ square yards}$.
The formula for the area of the triangle, Q, with two sides b and c and an angle A inscribed between those sides, is: $Q=\frac{1}{2}bc\sin A$ Putting the values in the formula, we get \begin{align} & \frac{1}{2}ac\sin B=\frac{1}{2}\left( 3 \right)\left( 6 \right)\left( \sin 36{}^\circ \right) \\ & =9\left( 0.587785 \right) \\ & =5.29 \\ & \approx 5 \end{align} The area of the triangle is approximately $5\text{ square yards}$.