The Brainliest Answer!
Two circles intersect at two points A and B

 AD and AC are diameters to the two circles

angle DBA and angle CBA = 90   ( Angle subtended by a Dianeter...)

Join DB and DC

angle DBA and angle CBA are linear pair...
therefore DBC is a line and point b lies on DC

Hope it is helpful...

diagram is given in the pic

2 4 2
if the answer satisfies you plese mark as brainliest
thnq... : )
thank u that was very useful