In the following figure ∠ABD = ∠BDC and ∠CBD = ∠ADB. Then, ABCD is a __________.
In the adjoining figure, ABCD is a parallelogram in which ∠BAD=75∘ and ∠CBD=60∘. Then, ∠BDC= ?
(a) 60∘
(b) 75∘
(c) 45∘
(d) 50∘