1.4 Angles Measure CCSS: G-CO.1 Experiment with transformations in the plane. G-CO.12 Make geometric constructions. Objective: Measure and classify angles

Ray: is a part of a line, it has an endpoint (starting point) and extends indefinitely Named EF, or EG E Q P P R Opposite Rays by definition are two collinear rays with a common endpoint

Angle An angle is formed by two non-collinear rays (called the sides) with the same initial point (called the vertex) C Vertex: point A Ray (Side) Sides: AB, and AC B A Ray (Side) Vertex

Naming Angles There are three ways to name angles C B A 4 1. By using the vertex 2. By using the points on the angle C 4 B 3. By using the number inside the angle A

Interior and Exterior of Angles An angle divides a plane into 3 distinct parts. On, In, or Outside ON Points A, D, and E lie _____________ the angle M IN Points C and B lie _____________ of the angle A C OUTSIDE B Points F and G lie _____________ of the angle E F D G

Example 1 p. 32 Angles and Their Parts W X V Name all the angles that have W as a vertex 2 1 3 Name the side of <1 5 4 Z Y Write another name for <WYZ

Notes #2 (1.4) continued 1.4 Angles Measure CCSS: G-CO.1 Experiment with transformations in the plane. G-CO.12 Make geometric constructions. Objective: Measure and classify angles Identify and use congruent angles and the bisector of an angle

Protractor Since QP is aligned It has two scales running w/ 0 the other side of the angle can be measured at 65 degrees It has two scales running from 0 to 180 degrees in opposite directions Align the 0 on either side of the angle The center point of the protractor is on the vertex

Classifying Angles 90 < m C < 180

Congruent Angles ~ m<A = m<B <A = <B Congruent Angles: are angles with the same measure or degree Angle congruence looks like this… ~ m<A = m<B <A = <B D B C A

Example In the figure, . If and . Find the measurements of A C B D F

Angle Bisector: a ray that divides an angle into two congruent angles Angle Addition When a line divides an angle into two smaller angles Then the sum of the smaller angles equals the larger angle m< RSP + m<PST = m<RST R P S T