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
∴ ∠OTA = 90°
In right ΔOTA, we have
OA2 = OT2 + AT2
⇒ OT2 = 676 – 100
= 576
= (24)2
⇒ OT = 24
Hence the radius of the circle is 24 cm.