The radius of a circle which has a 6 cm long chord, 4 cm away from the centre of the circle is
In the right triangle OAP,
OA2 = OP2 +AP2 (By Pythagoras theorem)
OA2 = 42 + 32 (perpendicular from the centre of the circle bisects the chord , AP=3cm)
OA2 = 25
OA = 5
Hence the radius of the circle is 5 cm.