### Home > GC > Chapter 6 > Lesson 6.2.2 > Problem 6-50

6-50.

**Examine** the diagram at right. Based on the information below, what statement can you make about the relationships between the lines? Be sure to justify each conclusion. Remember: each part below is a separate problem.

When do alternate interior angles have equal measures?

If and

*are parallel.*

If two angles which form a straight angle are equal, what must their measures be?

*n* is perpendicular to because

*and*

*are both*

Under what circumstances are vertical angles equal?

Is there anything special about angles that add up to