1. Angles  Learn to name and measure angles.

2. Lines and Rays: A Ray is part of a line. A Ray has one initial point and extends indefinitely in one direction. A line extends without end in both directions. Example: Line AB The symbol for line is AB Rays, like the sun’s rays, start at one point and continues without end in one direction. Example : The symbol for ray is OA

3. Angles:  When 2 rays have the same endpoint they form an angle.  The 2 rays are the sides of the angle and the common endpoint is the vertex.  You can use the angle symbol ( < ), the vertex, and a point on each side to name the angle. You can use the vertex alone, or a number to name the angle.  For example: <B, <ABC, < CBA

4. Angles can be measured in degrees:  An Acute Angle: has a measure of less than 90 degrees. Example:  A Right Angle: has a measure of exactly 90 degrees. Example:

5.  An obtuse Angle: has a measure greater than 90 degrees and less than 180 degrees. Example:  A Straight Angle: has a measure of exactly 180 degrees. Example:

6. Complementary and Supplementary Angles: Complementary Angles  Two angles that add up to 90 degrees.  For example: 30 0 + 60 0 = 90 0 So 30 and 60 are complementary angles. Supplementary Angles Two angles that add up to 180 degrees. For example: 45 0 + 135 0 = 180 0. So, 45 and 135 are supplementary angles.

7. How to use a protractor to measure angles in 3 steps:

8. Homework: