ExplanationLet a and b be the sides of the parallelogram and β be the angle in between a and b.

Formula of parallelogram diagonal in terms of sides and cosine β (cosine theorem). In this case β=100.

Diagonal XZ = \(\sqrt{a^2 + b^2 - 2ab cos(\beta)}\) =\(\sqrt{a^2 + b^2 - 2ab cos(100)}\) =\(\sqrt{a^2 + b^2 + 2ab cos(80)}\).

Diagonal WY = \(\sqrt{a^2 + b^2 - 2ab cos(\beta)}\) = \(\sqrt{a^2 + b^2 - 2ab cos(80)}\).

Thus clearly XZ is greater. Hence option B is correct.Alternatively you can just remember that in a parallogram the diagonal opposite to the larger angle is greater in length than the other one.

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Sandy

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