Question

Two circles of radii 5 cm and 3 cm are concentric. Calculate the length of a chord of the outer circle which touches the inner.

Answer 1

OS = 5 cm

OT = 3 cm

In Rt. Triangle OST

By Pythagoras Theorem,

ST² = OS² – OT²

ST² = 25 – 9

ST² = 16

ST = 4 cm

Since OT is perpendicular to SP and OT bisects chord SP

So, SP = 8 cm