In the given figure AB and DC are two chords of a circle with centre O, which when produced meet at P. If PB = 7 cm, BA = 10 cm and PO =12cm, find the radius of the circle.
5 cm
Let the radius of the circle = r cm
∴OC=OD=r
PC=PO–OC=12–r
PD=PO+OD=12+r
Chords AB and DC intersect at P (given)
PA×PB=PC×PD
17(7)=(12–r)(12+r)
119=144–r2
r2=25
r=5 cm
Hence (D)