Angle Measure Section 1-4
Vocabulary Degree Ray Label Naming a ray – AM or AP
Opposite Rays Opposite rays are two rays with a common endpoint that form a line. R S T The opposite rays are SR and ST.
Angle 2 noncolinear rays that share a common endpoint. Angle Name R, SRT, TRS, or 1
Example 1 Name all of the angles in the diagram below RTQ, QTS, STR, 1, 2
Measuring Angles The measure of an angle is usually given in degrees. Since there are 360° in a circle, one degree is of a circle. You will use a protractor to find the measures of angles.
Example 2 - Find the measure of each angle Example 2 - Find the measure of each angle. Then classify each as acute, right, or obtuse. A. WXV mWXV = 30° WXV is acute. B. ZXW mZXW = |130° - 30°| = 100° ZXW = is obtuse.
Congruent Angles Congruent angles are angles that have the same measure.
An angle bisector is a ray that divides an angle into two congruent angles. JK bisects LJM; thus LJK KJM.