Three circles of radius 21 cm are placed in such a way that each circle touches the other two. What is the area of the portion enclosed by the three circles?

Answer: Option A

Area of portion enclosed by the three circles = Area of Equilateral triangle - 3 × Area of sector
$$\begin{array}{rl}& =\frac{\sqrt{3}}{4}\times {\left(\text{side}\right)}^2-\left(\pi r^2\left(\frac{\theta }{{360}^{\circ }}\right)\times 3\right)\\ & =\frac{1}{2}\left(\frac{\sqrt{3}}{4}\times 42\times 42-\frac{22}{7}\times 21\times 21\times \frac{1}{3}\times 3\right)\\ & =441\sqrt{3}-693\end{array}$$