For a △PQR with points P,Q and R lying on a circle, if RP is the diameter of the circle and PQ=5 cm and QR=12 cm. Find radius of the circle.
Because angle in a semicircle is always 90∘, so
So ∠RQP=90∘ and RP is the diameter
Thus by pythagorean theorem we have
RP2=RQ2+QP2
=122+52=169
RP=13=d=2r
r=6.5 cm