Three boys are standing on a circular boundary of a fountain. They are at equal distance from each other. If the radius of the boundary is 5 m, the shortest distance between any two boys is :

Answer: Option B

Let A, B and C denote the portions of the three boys
Then, AB = BC = AC
So, ΔABC is equilateral
Let the side of ΔABC be a
Then,
$$\begin{array}{rl}& \frac{a}{\sqrt{3}}=5\\ & \Rightarrow a=5\sqrt{3}\end{array}$$
∴ Required shortest distance = $$5\sqrt{3}m$$