# Ch 9: Parallel Lines and Polygons

Watch online math video lessons to learn about the parallel postulate, transverse lines, polygons and more. These lessons are just a portion of our test prep course for the NY Regents geometry exam.

## Parallel Lines and Polygons - Chapter Summary and Learning Objectives

In this chapter, our instructors demonstrate several methods for determining whether two lines will intersect or remain the same distance apart. They also show you how to put these concepts to use in order to find measurements for a polygon's interior and exterior angles. Watch the short video lessons included here to learn about the following:

• Uses of the parallel postulate
• Angles created by transverses lines
• Properties and types of polygons
• Polygons' interior and exterior angles

Video Objectives
The Parallel Postulate and Indirect Proof: Definition & Examples Learn how the parallel postulate can be used to prove lines are parallel.
Angles Formed by a Transversal Explore the relationship between the angles created when a line transverses two parallel lines.
Parallel Lines: How to Prove Lines Are Parallel Use pairs of corresponding, alternate interior and alternate exterior angles created by a transversal to prove lines are parallel.
Using Converse Statements to Prove Lines Are Parallel Find out how converse statements about a transversal can be used to prove lines are parallel.
What Are Polygons? - Definition and Examples Examine the differences between regular, irregular, concave, convex, simple and complex polygons.
Measuring the Area of Regular Polygons: Formula & Examples Use a regular polygon's apothem and side lengths to calculate the area.
Measuring the Angles of Triangles: 180 Degrees Explain how parallel lines can be used to prove the sum of a triangle's interior angles.
How to Measure the Angles of a Polygon & Find the Sum Determine the measurements of a polygon's interior and exterior angles.

9 Lessons in Chapter 9: Parallel Lines and Polygons
Test your knowledge with a 30-question chapter practice test
Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
Not Taken
Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
Not Taken

### Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.