Question

An equilateral triangle of side 9 cm is inscribed in a circle. Find the radius of the circle.

Answer 1

On measuring its radius, it is 5.2 cm

Radius $=\frac{2}{3}AD=\frac{2}{3}\times \frac{\sqrt{3}}{2}\times side$

$=\frac{2}{3}\times \frac{\sqrt{3}}{2}\times 9=3\sqrt{3}cm$

$=3\times 1.732=5.196=5.2cm$