Question

Look at the image please

Answer 1

AOC and BOD are diameters of circle O (given)

AC and BD bisect each other at O (diameters of a circle bisect each other)

AC = BD (diameters of a circle are congruent)

Angle BOA = angle DOC (vertical angles are congruent)

∆BOA = ∆DOC (SAS)

BA = DC (CPCTC)

Angle ABO = angle DCO (CPCTC)

Angle OAD = angle ODA (base angles of an isosceles triangle are congruent)

Angle BAD = angle CDA (angle addition)

∆ABD = ∆DCA (ASA)