Question

if angle BAO=angle DCO and OC=OD,show that AB||CD

Answer 1

the question was quiet simple

Answer 2

here OC=OD so triangle OCD is an isosceles triangle so Angle C=angle D.
now it is given that angle C=angle A but angle C=angle A therefore angles A,Candle D are equal. angle A=angle D by alternate interior angles and when a pair of alternate interior angles is equal then the lines are parallel. therefore AB ll CD.
hence Proved