Geometry Notes Section 1-4 Angle Measure Definition A ray is a part of a line with an endpoint that extends forever in one direction. . A . B Table Ray Drawing Facts . A . B has a beginning but not end Naming AB or ray AB Named by Letter on endpoint first then another point on the ray Definition Opposite rays – two rays that share the same endpoint but extend in two opposite directions. . . . R S T *SR and ST are opposite rays* Definition An angle is formed by two rays that share a common endpoint and nothing else. The two rays that make the angle are called the sides of the angle. The endpoint is called the vertex. • B is the vertex. • BT and BQ are the sides. Table Angle Drawing Facts 1. 2. Naming Named by Made of 2 noncollinear rays w/a common endpoint Can be measured in degrees B, TBU , UBT , 1 1.one point from one side then the vertex then a point from the other side,2. by the vertex,3. by a numbered angle What do angles do? Angles divide planes into 2 parts. 1. interior of an angle 2. exterior of an angle 1. Points D and E are in the interior 2. Point F is in the exterior Classifying Angles by Measure •If x is measure of the angle in degrees: Definition Congruent angles are angles that have the same measurement. mBAD mCAD congruent Definition An angle bisector is a ray that cuts an angle into two congruent angles. AD is an angle bisector Now it’s time for some heavy lifting! Hwk pg 34 #’s 12-33,35-36