- Acute: less than 90
^{o} - Adjacent angles: two coplanar angles with a common side, a common vertex, and no common interior points.
- Central Angle of a circle
- Complementary: Two angles whose sum is 90 °
- Inscribed Angle of a circle
- Linear pair of angles: angles that are supplementary and adjacent
- Obtuse:more than 90
^{o} - Supplementary: Two angles that add up to 180
^{o} -
Parallel Line Angles: Angles formed by Intersecting lines (corresponding, alternate interior, alternate exterior, same side interior)
- Interactive Parallel lines cut by a transversal (and all the angles: corresponding, alternate interior and exterior)

- Triangle's Angles
- Right Angles: exactly 90 °
- Vertical Angles
- Supplementary Angles
- Angles associated with more complex shapes
- Angles and circles
- Angles formed by intersection of secants, tangents outside of a circle