1. 4 Angles and Their Measures

1.4 Angles and Their Measures POD Fill in the blanks. 1. The endpoint of RQ is ____________. 2. Line segments with equal measures are __________. 3. A rule of geometry that is accepted without proof is a ______________. 4. A pair of opposite rays form a ___________.

1.4 Angles and Their Measures • Angle Parts • Consist of two different Rays. • The rays are called the sides of the angle. • The vertex is the initial point of the angle. • A point is interior of an angle if it is between the sides. • A point exterior of an angle if it is not.

1.4 Angles and Their Measures • Naming Angles • Name the angles in the figure: P Q S R <PQS or <SQP <SQR or <RQS <PQR or <RQP

1.4 Angles and Their Measures • Postulates 3 and 4 • Protractor Postulate • Consider a point on one side of OB. The rays of the form OA can be matched with the real numbers from 0 to 180. • The measure of <AOB is equal to the absolute value of the difference between the real numbers OA and OB. • Angle Addition Postulate • If P is in the interior of <RST, then m<RSP + m<PST = m<RST A R O B P S T

1.4 Angles and Their Measures • Classifying Angles • Acute • Between 0 and 90 degrees • Right • 90 degrees • Obtuse • Between 90 and 180 degrees • Straight • 180 degrees

1.4 Angles and Their Measures Closure Draw five points, A, B, C, D, and E so that all three statements are true. <DBE is a straight angle <DBA is a right angle <ABC is a straight angle

1.4 Angles and Their Measures • Let’s Practice!!!! • In your Textbook: pg. 29-30 DO #17, 21, 23-37, 39, 40-41

1. 4 Angles and Their Measures