Sections 1.3a and 1.4: Measuring Angles Rigor: Calculate the measure of angles using postulates, bisectors and angle pairs Relevance: Measuring angles allows us to calculate and communicate rotation.

What are angles? An angle is a figure formed by two rays, called sides, with a common endpoint called the vertex (plural: vertices). Naming angles: By the vertex R By a number in the interior 1 With 3 points: one from each side and the vertex in the middle SRT or TRS If more than 1 angle shares a vertex you can NOT name the angle solely by its vertex!

Example 1: Naming Angles A) What are two other names for B) Why can’t 1 be named

Measuring Angles Angles describe rotation, NOT length Angles are measured in degrees using a protractor or in radians. Read “the measure of angle AOB is 125 degrees”

Classifying Angles By Their Measure Angles with the same measure are congruent angles. Symbol for congruent angles in pictures

Example 2: Using Protractors Use a protractor to draw a 120o angle, a 90o angle, and a 40o angle. Classify each angle as acute, obtuse, right, or straight.

Calculate 𝒎∠𝑴𝑵𝑶 and 𝒎∠𝑷𝑵𝑶. Example 3: Example 4: Calculate 𝒎∠𝑴𝑵𝑶 and 𝒎∠𝑷𝑵𝑶. mDEG = 115°, and mDEF = 48°. Find mFEG. x 3x - 2 M P N O

Angle Bisectors An angle bisector is a ray that divides an angle into two congruent angles. JK bisects LJM; thus LJK  KJM.

Example 5 KM bisects JKL, mJKM = (4x + 6)°, and mMKL = (7x – 12)°. Find mJKM.

1.3a Classwork (not graded) Textbook pg 24 – 26 #3, 8, 12, 17, 27, 29, 34 (Honors also 18)

1.4 Notes: Angle Pairs Workbook pgs 22 – 23 Vocabulary words: vertical angles, adjacent angles, complementary angles, and supplementary angles Complete examples 2 & 3 along with the reflection questions Example 4: The mD = (2x + 5)o. What is the measure of the supplement of mD?

1.3a/1.4 Assignments Primary Assignment: Secondary Assignment: Website: join.quizizz.com Codes: Period 1: 089750 (Due Thurs 8/23 at 7AM) Period 3: 409782 (Due Thurs 8/23 at 7AM) Period 7: 237964 (Due Fri 8/24 at 7AM) Secondary Assignment: Textbook pg 24 – 26 #9, 11, 14, 24, 30, 34, 41, 45 Workbook pg 24 ALL

1.3a/1.4 Assignments Primary Assignment: Due Friday 8/24 at 7AM Website: join.quizizz.com Codes: Period 2: 754680 Period 4: 844362 Period 6: 384464 Secondary Assignment: Textbook pg 24 – 26 #9, 11, 14, 24, 30, 34, 41, 45 Workbook pg 24 ALL