Two persons are on either side of a temple, 75 m high, observe the angle of elevation of the top of the temple to be 30 and 60 deg respectively. The distance between the persons is
A circle has its centre at O . A tangent drawn from a point P , which is situated outside the circle, touches the circle at A. If PA = 4 cm & PO=5 cm, then the length of the radius of the circle is