1. 71.vo circles of radii 5 cm and 3 cm intersect at two points and the distance between their centres is 4 cm. Find the length of the common chord.

We know that line joining the centres is perpendicular bisector of the common chord. The common chord passes through the centre of the smaller circle. .. LPAO = 90°, OA = 4 cm and OP = 5 cm. .. Applying Pythagoras theorem, we have PA = (5")2 - (4)2 cm = .J20 -16 cm J9 cm = 3 cm. = Further, PQ = 2PA = 2 x 3 = 6 cm.