CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) What is an

angle? Two different

rays with the same endpoint.

Rays are the sides, endpoint is the vertex.

Named with 3 points or by the vertex.

vertexsides

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Example Name the angles

you see in the diagram

A

C

D

E

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Measuring

angles with a protractor

Different types of angles:

Write either <ABC is 32º or m<ABC=32º

Acute (less than 90º)

Obtuse (more than 90º

Right angle (exactly 90º)

Straight (180º)

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Example

Postulate 4: Angle Addition

Page 25 in textbook

If P is in the interior of <RST, then the measure of <RST is equal to the sum of the measures of <RSP and <PST

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Example Given the

m<GFJ=155º, find m<GFH and m<HFJ

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Example Given that <VRS

is a right angle, find m<VRT and m<TRS

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Congruent

angles 2 angles are

congruent if they have the same measure (curved line)

<A <B

A

B

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Example Identify all pairs

of congruent angles

If m<P=120º, what is m<N?

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES) Angle Bisector A ray that

divides an angle into 2 angles that are congruent.

WY bisects <XWZ

CHAPTER 1-4 (MEASURE AND CLASSIFY ANGLES)Examples