Let two circles having their centres as O and O' intersect each other at point A and B respectively.
Let us join OO'.
In ΔAOO'and ΔBOO',
OA = OB (Radius of circle 1)
O'A = O;B (Radius of circle 2)
OO' = OO' (Common)
Δ AOO' ≅ ΔBOO' (By SSS congruence rule)
∠OAO' = ∠OBO' ( by CPCT),
Therefore, line of centres of two intersecting circles subtends equal angles at the two points of intersection.