Prove that the line of centers of two intersecting circles subtends equal angles at the two points of intersection.

Let two circles with centers as O and O’ intersect each other at point A and B respectively Join OO’.

Now,


In ΔAOO’ and BOO’


O’A = O’B (radius of same circle)


OA = OB (Radius of same circle)


OO’ = OO’ (Common)


Hence, by SSS congruence


ΔOAO’ ΔOBO’


OAO’ = OBO’ (By CPCT)


Therefore,


Line of centers of two intersecting circles subtends equal angles at the two points of intersection


3