### Unit 2: Parallel and Perpendicular Lines

Simply put, parallel lines are lines in a plane that do not intersect, while perpendicular lines are lines that intersect at a right angle (90°). Parallel and perpendicular lines are all around us. For example, railroad tracks, iron fencing, latticework, and kitchen tables all have parallel and/or perpendicular lines.

Have you ever looked at a tile floor that has an intricate pattern of crisscrossing lines? The pattern has to be carefully replicated, following special rules. When parallel lines cross other lines, they create their own set of special rules, which may be used in making these patterns. In this unit, you will learn what happens when parallel lines cross other lines and how all the created angles relate to each other.

**Completing this unit should take you approximately 10 hours.**

Upon successful completion of this unit, you will be able to:

- determine the distance between two points;
- determine the lengths of a line segment's sections; and
- find the measure of angles created by parallel lines and transversals.

### 2.1: Lines

### 2.1.1: Parallel, Perpendicular, and Skew Lines

Study the "Lines and Angles" section. This section provides examples of parallel, perpendicular, and skew lines.

Take notes as you watch this video to learn how to identify parallel and perpendicular lines. Watch the presentation carefully two to three times to identify parallel and perpendicular lines.

### 2.1.2: Angles and Transversals

Study this section. This section provides examples of different angles with a transversal line.

Study this section. This section provides examples of perpendicular lines.

### 2.2: Angles and Lines

### 2.2.1: Corresponding Angles

Take notes as you watch the videos and read this section to learn about corresponding angles. This section provides examples of corresponding angles. Then, complete exercises 1-15. These exercises will provide you with the opportunity to determine angles using corresponding angles. Once you have completed the exercises, check your answers against the linked answer key.

### 2.2.2: Alternate Interior Angles

Take notes as you watch the videos and read this section to learn about alternate interior angles. This section provides examples of corresponding angles. Then, complete exercises 1-15. These exercises will provide you with the opportunity to determine angles using alternate interior angles. Once you have completed the exercises, check your answers against the linked answer key.

### 2.2.3: Alternate Exterior Angles

Take notes as you watch the videos and read this section to learn about alternate exterior angles. This section provides examples of alternate exterior angles. Then, complete exercises 1-15. These exercises will provide you with the opportunity to determine angles using alternate exterior angles. Once you have completed the exercises, check your answers against the linked answer key.

### 2.2.4: Same Side Interior Angles

Take notes as you watch the videos and read this section to learn about same side interior angles. This section provides examples of same side interior angles. Then, complete exercises 1-15. These exercises will provide you with the opportunity to determine angles using alternate exterior angles. Once you have completed the exercises, check your answers against the linked answer key.

### 2.2.5: Angle Game

Take notes as you watch these videos to learn how to identify corresponding, alternate interior, alternate exterior, and same side-interior angles. Watch the presentations carefully to understand the angle within each problem and how they are intertwined.

Complete this assessment, which tests your knowledge on corresponding, alternate interior, alternate exterior, and same side interior angles. You can review the concepts associated with these questions with the Khan videos in sub-subunit 2.2.5.

Complete this assessment, which tests your knowledge on corresponding, alternate interior, alternate exterior, and same side interior angles. You can review the concepts associated with these questions with the Khan videos in sub-subunit 2.2.5.

### 2.3: Distance Formula in the Coordinate Plane

Take notes as you watch the videos and read this section to learn about find the distance between two points in the coordinate plane. This section provides examples of find the distance between two points in the coordinate plane. Then, complete exercises 1-8 and 13. These exercises will provide you with the opportunity to find the distance between two points in the coordinate plane. Once you have completed the exercises, check your answers against the linked answer key.