1. Angle Measure Section 1-4

2. angle – a figure consisting of 2 noncollinear rays with a common endpoint. The 2 rays are called the sides of the angle. The common endpoint is called the vertex.

3. A ray extends indefinitely in one direction. A ray has exactly one endpoint and that endpoint is always used first when naming the ray. A B

4. 2 opposite rays form a line. A B C

5. interior exterior An angle separates a plane into 3 parts, the interior of the angle, the exterior of the angle, and the angle itself.

6. The sides of the angle are. The vertex is B. You could name this angle as B A C 1

7. Right angle = 90 0 Acute angle < 90 0 Obtuse angle > 90 0

8. Angle Bisector – a ray that divides an angle into 2 congruent angles 1 Angles that have the same measure are congruent. 2 Angle bisector