**Data:** 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.

**To Prove: **Length of wire of telephone = ?

**Proof:** In this figure, AS = SD = DA

∴ ASD is an equilateral triangle.

∴ OA = 20 m.

(∵ radius) Median passed through centre of circle.

∴ AB is the median. AD⊥SD

Median of equilateral triangle divides in the ratio 2 : 1 in the centre?

∴ AO : OB = 2 : 1