Step 1: Observe the given figure for the hints

NOTE: triangle is a equilateral triangle

Inscribed circle with in-center O

AOP triangle is a right triangle

Step 2: Find the area of the right triangle

\frac{1}{2} (b * h)

Step 3: Find the base and height of the right triangle

NOTE: OP is perpendicular to AC at middle point

Base b = \frac{side}{2} = \frac{10}{2}

Height h = radius of the inscribed circle = side *\frac{\sqrt{3}}{6}

h = 10 * \frac{\sqrt{3}}{6}

Skill 3: Plugging the base and height values in the formula

\frac{1}{2} *\frac{10}{2}*10 * \frac{\sqrt{3}}{6}

25 \frac{\sqrt{3}}{6}