Definition: An angle whose measure is greater than 90° and less than 180°

Try this
Adjust the angle below by dragging the orange dot at A and see how the angle ∠ABC behaves.
Note that it is obtuse for all angles greater than 90° and less than 180°

Acute angle Less than 90° |
Right angle Exactly 90° |
Obtuse angle Between 90° and 180° |

Straight angle Exactly 180° |
Reflex angle Between 180° and 360° |
Full angle Exactly 360° |

- Vertical angles
- Complementary angles
- Supplementary angles
- Linear pair
- Adjacent angles
- Corresponding angles
- Alternate interior angles
- Alternate exterior angles
- Interior angles of a transversal
- Exterior angles of a transversal

(C) 2011 Copyright Math Open Reference.

All rights reserved

All rights reserved