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ABCD is a cyclic trapezium whose sides AD and BC are parallel to each other. If ∠ABC = 75° then the measure of ∠BCD is :
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- 75°
- 95°
- 45°
- 105°
- 75°
Correct Option: A
As per the given in question , we draw a figure cyclic trapezium ABCD 
Given , ∠ABC = 75°
ABCD is a concyclic quadrilateral.
AD || BC
∴ ∠DAB + ∠ABC = 180°
⇒ ∠DAB = 180° – 75° = 105°
Sum of the opposite of a concyclic quadrilateral = 180°
∴ ∠BAD + ∠BCD = 180°
⇒ 105° + ∠BCD = 180°
⇒ ∠BCD = 180° – 105° = 75°
