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Supplementary Angles
From Latin: supplementum - "something added to supply a deficiency"
Definition: Two angles that add up to 180°
Try this Drag an orange dot. The two angles will change so that they always add to 180°
(If there is no image below, see support page.)
In the figure above, the two angles ∠PQR and ∠JKL are supplementary because they always add to 180° Often the two angles are adjacent, in which case they form a straight angle. Similar in concept are complementary angles, which add up to 90°. A way to remember
Sometimes it's hard to remember which is which between supplementary (adds to 180°) and complementary (adds to 90°).
One phrase that may help is "it's right to give compliments" A right angle is 90 degrees and, yes, 'compliment' and 'complement' are not the same word, but it's a way to remember which is which. Related angle topicsGeneralAngle TypesAngle relationships
(C) 2008 Copyright John Page
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