Geometry: 1,001 Practice Problems For Dummies (+ Free Online Practice)
Book image
Explore Book Buy On Amazon

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


Answers and explanations

  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


About This Article

This article is from the book:

About the book authors:

Allen Ma and Amber Kuang are math teachers at John F. Kennedy High School in Bellmore, New York. Allen, who has taught geometry for 20 years, is the math team coach and a former honors math research coordinator. Amber has taught all levels of mathematics, from algebra to calculus, for the past 14 years.

This article can be found in the category: