Geometry: 1,001 Practice Problems For Dummies (+ Free Online Practice)

When two parallel lines are intersected by a third line (called a transversal), congruent pairs of angles are formed, including alternate interior angles and alternate exterior angles.

The following practice questions ask you to use this information to find a missing angle, and then to apply some algebra to calculate a missing variable.

Practice questions

Use the diagram and the given information to solve the problem.

1. Parallel lines

are cut by a transversal. If

is represented by

is represented by 4x – 45, find the value of x.

2. Parallel lines

are cut by a transversal. If

are represented by

respectively, find the degree measure of

1. 20

are alternate interior angles. Alternate interior angles are congruent, so set their measures equal to each other and solve for x:

2. 140 degrees

are alternate exterior angles. Alternate exterior angles are congruent, so set their measures equal to each other and solve for x:

which means they add up to 180 degrees. Use this info to solve for