Corresponding Angles
Corresponding angles are pairs of angles that are formed when a transversal crosses two parallel lines. These angles occupy the same relative position at each intersection.
- Properties:
- They are equal in measure.
- For example, if two parallel lines are cut by a transversal, angle A and angle F (corresponding angles) are equal.

Alternate Interior Angles
Alternate interior angles are the angles that lie between two parallel lines but on opposite sides of the transversal.
- Properties:
- They are also equal in measure.
- For example, if two parallel lines are intersected by a transversal, angle C and angle D are alternate interior angles.

Co-Interior Angles
Co-interior angles, also known as consecutive interior angles, are the pairs of angles that are on the same side of the transversal and lie between the two parallel lines.
- Properties:
- The sum of co-interior angles is supplementary, meaning they add up to 180 degrees.
- For instance, if angle E and angle H are co-interior angles, then E + H = 180°.

Conclusion
Understanding these angle types is crucial in geometry, especially when working with parallel lines and transversals. Recognizing their properties allows for easier problem-solving and proofs in mathematics.