In figure PA and PB are tangents from P to the circle with centre O. R is a point on the circle. Prove that : PC + CR = PD + DR
∴ Tangents drawn from an external point of a circle are equal
∴ BP = BR = 3 cm
AQ = AR = 4 cm
PC = CQ = AC – AQ = 11 cm – 4 cm = 7cm
Now, BC = BP + PC = 3 cm + 7 cm = 10 cm