Q18 of 115 Page 8

The opposite sides of a quadrilateral are parallel. If one angle of the quadrilateral is 60° find the other angles.

AB ‖ CD and AD is transversal

AD ‖ BC


Therefore,


∠A + ∠D = 180o(Co. interior angles are supplementary)


60o + ∠D = 180o


∠D = 120o


Now,


AD ‖ BC and AB is transversal


∠A + ∠B = 180o(Co. interior angles are supplementary)


60o + ∠B = 180o


∠B = 120o


Hence,


∠A = ∠C = 60o


∠B = ∠D = 120o


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