Question

Which angles are not supplementary

Answer 1

Answer: Choice c)

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Explanation:

Choice a) can be ruled out because angles A and D are supplementary. Supplementary angles add to 180 degrees by definition. They form a straight line or straight angle.

Choice b) and choice d) are eliminated for similar reasoning as choice a).

Choice c) is the only thing left. It turns out that angles B and D are not supplementary, but rather they are vertical angles. They are opposite one another in this X shape. Vertical angles are always congruent.

Note: Angles B and D are supplementary if and only if the angles are 90 degrees each.