Quadrilateral ABCD has its diagonals AC and BD intersecting at the point O. It is given that AO=CO, BO=DO and ∠AOB=∠COD.
(a) Prove that △AOB≅△COD.
(b) Prove that △BOC≅△DOA.
(c) Using the results of parts (a) and (b), explain why AB=CD and AD=BC. Give clear reasons for every statement you make.