The diagonals AC and BD of a parallelogram ABCD intersect each other at the point O . If ∠DAC=35∘ and ∠AOB=80∘, then ∠DBC is equal to ___.
45∘
Let ∠DBC be 'x'
∠DAC=∠ACB=35∘ [Alternate angles]
Consider
∠AOB+∠BOC=180∘ [ Linear pair]
∠BOC=180∘−80∘=100∘
Consider ΔBOC,
∠BOC+∠OCB+∠CBO=180∘
100∘+35∘+x=180∘
x=180−135=45∘
∴∠DBC is 45∘