Question

The length of a tangent from a point A at distance 5 cm from the centre of the circle is 4cm. Find the radius of the circle.
​

Answer 1

Let abo be the ∆

where ab is the tangent

this L b = 90°

and oa = hypotenuse

ob is the radius,

Given,

oa=h= 5cm

ab=p=4cm

ob=b=?

h²= p²+b²

(5cm²)= (4cm)²+b²

b²= 25cm²-16cm²

b= √9cm²

=3cm

therefore, the radius is 3cm.