Angles
Angles are fundamental to the study of Geometry. All geometry shapes have angles. Each angle has unique properties. The three angles are: obtuse angles, acute angles, and right angles.
What is an obtuse angle?

An obtuse angle is one the is larger than 90 degrees or right angle but less than 180 degrees. Examples of obtuse angles are shown below. The red circles show where the obtuse angle is on each triangle. 
What is an acute angle?

An acute angle is one that is less than 90 degrees but more than zero. Examples of acute angles are shown below. The red circles show where the acute angle is on each geometry shape. 
What is right angle?
A right angle is one that is exactly 90 degrees. A right angle is the angle between two perpendicular lines or planes. Below are examples of right angles of geometry shapes. The red circles show each right angle. 

