Q.

Two concentric circles are of radii 5 cm and 3 cm. Find the length of the chord of the larger circle which touches the smaller circle.


Ans.

(8)

Let O be the centre of the concentric circle of radii 5 cm and 3 cm respectively. Let AB be a chord of the larger circle touching the smaller circle at P

Then AP = PB and OPAB

Applying Pythagoras theorem in OPA, we have

OA2=OP2+AP225=9+AP2

AP2=16AP=4cm

       AB=2AP=8cm