Question

A point A is 17cm from the centre of the circle. The length of the tangent drawn from A to the circle is 15cm. find the radius of the circle.

Answer 1

OA ⊥ AP (radius is perpendicular to tangent at the point of contact) 

In right  Δ OAP, 

OP² = OA² + AP² 

AP² = 17² + 15² 

= 289 - 225

= 64

AP = 8

The radius of the circle is 8 cm.