Angles and Lines

Key Terms Vertex - The common endpoint of two rays Angle - The formation of two common rays Right Angle - An angle that makes a "squared corner" and measures exactly 90° Acute Angle - An angle that measures less than 90° Obtuse Angle - An angle that measures more than 90° but less than 180° Straight Angle - An angle that measures exactly 180° Reflex Angle - An angle that measures more than 180° but less than 360° Vertical Angle - Angles that are opposite each other and are always equal or congruent Transversal - A line that cuts through two parallel lines forming eight angles. Horizontal lines - Run across from left to right or right to left Vertical lines - Run up and down from top to bottom or from bottom to top Parallel lines - Always run in the same direction; they never cross one another and keep an equal distance between them at all times Perpendicular lines - Run in opposite directions and one line crosses the other. When perpendicular lines cross, they form a right angle

 On the GED Test, you will be expected to identify different kinds of angles and their relationships to each other. What do angles and lines have to do with real life? Just like flies at a picnic, they are everywhere! Every time you look at a clock, walk through a door, or open a window, you see angles and lines.

 When playing different types of games, a person who understands angles and lines will have an advantage. For example, you need to see and read angles and lines when you play pool or tennis.

 This lesson will focus on the 4 different kinds of lines:

 Click the names to see examples of the lines.

 Horizontal and vertical lines do not need a lot of explanation, but you need to be sure not confuse them. In your town or community, you have streets or roads that run parallel to each other. This means they never cross each other. If you look at the map of a town or city, you will see many streets that "intersect," or meet at some point. Many of those streets run perpendicular to each other, and they may form a right angle at their point of intersection. A right angle measures 90 degrees. You will learn more about angles shortly. For now, just remember that a right angle looks like the angle where two walls come together.

Are you ready to test your knowledge of lines?