## Precalculus (10th Edition)

$27.81$ square units
By Heron's formula, the area $K$ is given as $K=\sqrt{s(s-a)(s-b)(s-c)}$, where $s=\frac{a+b+c}{2}$ Hence here $s=\frac{7+8+10}{2}=12.5$, $K=\sqrt{12.5(12.5-7)(12.5-8)(12.5-10)}\\$ $K\approx27.81$ square units