Question

draw an equilateral triangle of side root 21 cm​

Answer 1

Step-by-step explanation:

The length of side of equilateral triangle s = 21 cm is a chord of a circle. There are 2 radii at 120° in the isosceles triangle formed. By the sine rule: r/(sin 30°) = 21/(sin 120°) => r = 21(sin 30°)/(sin 120°) = 7(sqrt(3)) cm. Area of circumcircle = pi(7(sqrt(3))^2 = 147pi = 461.81 cm^2.