Parallel and perpendicular line segments  Angles and Lines
Parallel and perpendicular line segments
In this lesson, we will learn:
 How to measure and draw angles using a protractor
 How to identify whether pairs of lines or line segments are parallel or perpendicular
Notes:
 Protractors are used for measuring and drawing angles:
 The middle of the flat side of the protractor goes on the vertex of the angle
 There are two scales on the protractor from 0° to 180° (one going the clockwise way, one going the counterclockwise way)
 Line up one of the zeroes on the protractor with one arm of the angle and start measuring from 0° until you reach the other arm
 Two lines or line segments can either intersect (cross) each other or be parallel. In this section, we will be learning how to identify and draw parallel and perpendicular line segments. Parallel line segments never meet, no matter how far they are extended. Two line segments are perpendicular if they form a 90 degree angle where they cross. Parallel and perpendicular line segments are found everywhere in the world around us. For example, city planners often design roads to be parallel and perpendicular to each other. Along with roads, railroad tracks, lines on notebook paper, and bookcases are parallel.
 When two figures are parallel with each other we can use the symbol: $\parallel$
 When two figures are perpendicular with each other we can use the symbol: $\perp$
Related Concepts
 Parallel line equation
 Perpendicular line equation
Lessons

Intro Lesson

2.
Below is a line segment, AB.

4.
Parallel or not parallel
Are these line segments parallel? Answer YES or NO. 
5.
Perpendicular or not perpendicular
Are these lines perpendicular? Answer YES or NO.