#### Answer

( 25$\sqrt 3$ - $\frac{25 \pi}{2}$) $cm^{2}$

#### Work Step by Step

To find the area A of the shaded region
Area of triangle = Area of shaded region +3 * Area of sector
Area of shaded region = Area of triangle - 3 * area of sector
As we know area of equilateral triangle = $\frac{\sqrt 3}{4} side^{2}$
Area of Sector = $\frac{m}{360}$ * $\pi r^{2}$
= $10^{2} \frac{\sqrt 3}{4}$ - 3 * $\frac{60}{360} \pi 5^{2}$
=$100 \frac{\sqrt 3}{4}$ - 3 * $\frac{1}{6} \pi * 25$
=( 25$\sqrt 3$ - $\frac{25 \pi}{2}$) $cm^{2}$