∠BAC = 60°
∠BOC = 120°
The angle made by any arc of a circle on the alternate arc is half the angle made at the centre.
OB = OC (Raduis)
\(\angle BAC=\frac{1}{2}\times120=60^\circ\)
\(\angle BOC=180-(60+90)=30^\circ\)
The sides of the right angle triangle ΔCOD with angles 30°, 60°, 90° are proportional to the number 1 : √3: 2 .
BC = 3 cm
∴ DC = 1.5 cm.
OD = \(\frac{1.5}{\sqrt{3}}\) cm
Radius of circle = √3 cm
