Question

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

Answer 1

Step-by-step explanation:

we know that that ∠ADC would be equal to 90° by construction.

And BD = DC

Now,

∠B = 60° { given }

∠OBD = 30° { half of 60° as BO bisects ∠B }

in triangle OBD

cos30 = base/hypotenuse

✓3/2 = 4.5/hypotenuse

hypotenuse = radius = 3√3 cm