Lines CD and EH are parallel. Line AB is a transversal.

Remember when naming these angles, use three letters.
1. Use points, A, B and C to move the lines around the screen making sure to observe the values of the angles.
2. How many pairs of corresponding angles are there? Name them.
3. How many pairs of alternating interior angles are there? Name them.
4. How many pairs of alternating exterior angles are there? Name them.
5. How many pairs of same side interior angles are there? Name them.
6. How many pairs of vertical angles are there? Name them.
7. What conclusion can you make about each theorem?