Given: ABCD, ABEF are two cyclic quadrilaterals and ∠BCD = 110°

In Quadrilateral ABCD

We know that,

In a cyclic quadrilateral opposite angles are supplementary

∴ ∠BCD + ∠BAD = 180°

110° + ∠BAD = 180°

∠BAD = 180° – 110° = 70°

Similarly in Quadrilateral ABEF

∴ ∠BAD + ∠BEF = 180°

70° + ∠BEF = 180°

∠BEF = 180° – 70° = 110°

∴ ∠BEF = 110°