1. Use a protractor to draw angles with the following measurements:
Warm Up
Use a protractor to draw angles with the following measurements:
48⁰
110⁰ 5⁰
175⁰

2. Combining Angles

3. Congruent Angles = = STV PQR STV m PQR 100⁰
Congruent angles – have the same measure.
PQR
STV
Example: or
PQR m
STV = =
100⁰

4. Angle Addition Postulate
Angle Bisector
An angle bisector is a ray that divides one angle into two congruent angles
Ray YW bisects
XYZ

5. Example – Angle Addition Postulate
= 2(23) + 10
= = 56⁰
= 4x - 3 +
= 145⁰
= 4(23) - 3
(2x + 10) + (4x – 3) = 145⁰
= = 89⁰
6x + 7 = 145
Combine like terms
6x = 138
Subtract 7 from both sides
x = 23
Divide both sides by 6

6. Angle Pairs
Complementary angles – two angles whose measures add up to 90⁰
Supplementary angles – two angles whose measures add up to 180⁰
Adjacent angles – two angles that share a common vertex and side

7. More Angle Pairs
Vertical angles – sides form two pairs of opposite rays
Linear Pairs– two angles are a linear pair when their non-
common sides are opposite rays
non - common side
non - common side

8. Draw two congruent angles (any kind). Label the measure.
Whiteboard Activity
Draw an acute angle labeled
ABC
Draw two adjacent angles
Draw two adjacent angles that are complimentary
Draw one angle and label the vertex and sides.
Draw an obtuse angle labeled
JKL
Draw a straight angle.
Draw a right angle labeled
XYZ
Then draw a ray YW that is a bisector of that angle.