Diagonals of a parallelogram ABCD intersect at O. If ∠BOC = 90^o and ∠BDC = 50^o, then ∠OAB is Diagonals of a parallelogram ABCD intersect at O. If ∠BOC = 90^o and ∠BDC = 50^o then ∠OAB is July 1, 2021 Category: Chapter 8 - Quadrilaterals , Maths , NCERT Class 9 ,