Math Playground
Geometry

Complementary & supplementary

Two angles that add to 90° — or to 180°.

Two angle pairs that come up everywhere.

The pair rules

  • Complementary — two angles summing to 90°.
  • Supplementary — two angles summing to 180°.
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Complement of 35°

90° − 35° = 55°.

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Supplement of 110°

180° − 110° = 70°.