- An angle less than 90 is called an acute angle.
- An angle of 90 is called a right angle.
- An angle between 90 and and 180 is called an obtuse angle.
- An angle of 180 is called a straight angle.
- An angle between 180 and 360 is called a reflex angle.
- Angles on a straight line add up to 180.
Angles inside a triangle add up to 180. This can be shown by tearing a triangle into 3 pieces, with a corner in each. Join the corners together to make a straight line. Because there are 180 on a straight line there must be 180 in a triangle.
- An angle is an amount of turn measured in degrees.
- Make sure you know this…