**A circular park of radius 20 m is situated in a colony. Three boys Ankur, Syed and David are sitting at equal distance on its boundary each having a toy telephone in his hands to talk each other. Find the length of the string of each phone.**

**Solution:**

Suppose that points A, S and D represent Ankur, Syed and David respectively. According to the given situation, we have equilateral triangle .

Radius of the circle **m**

By property of equilateral triangles, we have

**m**

On , By using Pythagoras theorem, we can say that

**m**

By one of the property of equilateral triangles, AP is the perpendicular bisector of DS.

**m**

Therefore, length of the string of each phone **m**