Math Playground
Geometry

Complementary & supplementary

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

Two angle pairs that come up everywhere.

Drag the ray
35°
35°
acute angle
complement = 55°
Drag the ray
110°
110°
obtuse angle
supplement = 70°

The pair rules

  • Complementary — two angles summing to 90°.
  • Supplementary — two angles summing to 180°.
Try it

Complement of 35°

90° − 35° = 55°.

Try it

Supplement of 110°

180° − 110° = 70°.