### Home > CC3 > Chapter Ch9 > Lesson 9.1.1 > Problem 9-8

9-8.

Use the conjectures and definitions in this lesson to solve parts (a) and (b). Each part is a separate problem.

If

, find andby calculation.Angle 1 and angle 2 are alternate interior angles.

When the lines are parallel, alternate interior angles have equal measures.

If

and , write an equation and find .Disregard your calculations for angle measure from part (a).

If

and , write an equation to find . Then find.Since the lines are parallel, angles 1 and 2 have equal measure.