Question

In a trapezium ABCD, side AB is parallel to side DC. If
A = 78º and C = 120°, find angles B and D.​

Answer 1

Step-by-step explanation:

AB || DC and BC is transversal ∴∠B and ∠C, ∠A and ∠D are Cointerior angles with their sum = 180° i.e. ∠B + ∠C = 180° ⇒ ∠B + 120° = 180° ⇒ ∠B = 180° – 120° ⇒ ∠B = 60° Also ∠A + ∠D = 180° ⇒ 78° + ∠D = 180° ⇒ ∠D = 180° – 78° ∠D = 102