You should know the following angle facts:
An ACUTE angle is between 0º and 90º
A RIGHT angle is exactly 90º
An OBTUSE angle is between 90º and 180º
A STRAIGHT LINE angle is exactly 180º
A REFLEX angle is between 180º and 360º
There are 180º at angles that meet at a point on a straight line.
There are 360º at angles that meet at a point.
A ¼ turn is 90º
A ½ turn is 180º
A ¾ turn is 270º
A whole turn is 360º