Prove PQRS is a parallelogram.?

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1 Answer
Nov 21, 2017

see explanation.

Explanation:

enter image source here
As shown in the figure, a transversal passes through two parallel lines LandM,
As LandM are parallel, the alternate interior angles are equal, ASQ=DQS=2α,andBSQ=CQS=2β,
SP,SR,QPandQR are the bisectors of the interior angles,
As 2α+2β=180,α+β=90
SPQ=QRS=180(α+β)=90
Hence, S,P,Q,andR form a rectangle.