1. 1.5 Measuring Angles Student Learning Goal:
Students will measure angles and classify them by their size.
Students will apply the Angle Addition Postulate.

2. 1.5 Angle Measure
Degree – A unit of measure used in measuring angles. 1° is 1/360 of an entire circle.
An angle is formed by 2 noncollinear rays that have a common endpoint.
The rays are called sides of the angle.
The common endpoint is the vertex.

3. Example 1: Name all angles that have B as a vertex.
Name the sides of 5.
Write another name for 6.
Example 4-1a

4. Classifying Angles
• Right angle Acute angle m<A = 90° m<B is less than 90° Obtuse angle m<C is less than 180° & greater than 90°

5. Example 2:
SIGNS A railroad crossing sign forms congruent angles. In the figure, WVX ZVY. If mWVX a and mZVY a – 20, find the actual measurements of WVX and ZVY.
Example 4-3d

6. Example 3:

7. Angle Bisector
A ray that divides an angle into two congruent angles is called an angle bisector.

8. 𝑋𝑅 𝑏𝑖𝑠𝑒𝑐𝑡𝑠 ∡𝑊𝑋𝑍 𝑎𝑛𝑑 𝑋𝑆 𝑏𝑖𝑠𝑒𝑐𝑡𝑠 ∡𝑅𝑋𝑍.
Example 4:
𝑋𝑅 𝑏𝑖𝑠𝑒𝑐𝑡𝑠 ∡𝑊𝑋𝑍 𝑎𝑛𝑑 𝑋𝑆 𝑏𝑖𝑠𝑒𝑐𝑡𝑠 ∡𝑅𝑋𝑍.
1.) Find h if m∡𝑅𝑋𝑆=5ℎ+3 𝑎𝑛𝑑 𝑚∡𝑆𝑋𝑍=2ℎ+6.
2.) Find b if ∡𝑊𝑋𝑅=2𝑏+1 𝑎𝑛𝑑 ∡𝑊𝑋𝑍=86°. Z R S W R X

9. HW pgs
# 3, 4, 8, 9-14, 17-18, 21-30