Question

Find the length of the tangent from a point which is at a distance of 5cm from the centre of the circle of radius 3cm.

Answer 1

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

In right Δ OAP, 

OP² = OA² + AP² 

AP² = 5² -3² 

= 25 - 9 = 16

AP = 4 cm 

The length of the tangent is 4cm .