6.1 Angles


Angle Definition
The space (usually measured in degrees) between two lines or surfaces that intersect at or near the point where they meet.

Right Angle

  • The exact angle is 90°.
  • Only right angles have a small square between the two lines.


Acute Angle

  • An angle smaller than a right angle.
  • An acute angle is an angle smaller than 90° (< 90°).


Obtuse Angle

  • An angle greater than a right angle.
  • Angle of deflection exceeds 90° but does not exceed 180° (90°< obtuse angle < 180°).


Reflex Angle

  • An angle greater than the obtuse angle.
  • The reflex angle exceeds 180° but does not exceed 360° (180°< reflex angle < 360°).