Question

Two circle with centre O and O' intersect at A and B. AC and AD are respectively the diameters of the two circle. Prove that the point C, B and D are collinear

Answer 1

TO PROVE : CBD are collinear

PROOF: ∠ABC = 90° (angles on the semicircle )..........(1)
∠ABD = 90°(angles on the semicircle)...........................(2)
adding 1 and 2 we get,
∠ABC+∠ABD = 90°+90°
∠CBD=  180°
∴ CBD is a straight line hence collinear 

PROVED ........

Answer 2

as AC and AD are the diameters 
angle ABC and angle ABD are 90 °
adding both we get 180°
and the points are collinear 

CHANDRAVILAS0 HAS ANSWERED THE QUESTION CORRECTLY