What is an angle? Two different rays with the same endpoint. Rays are the sides, endpoint is the vertex. Named with 3 points or by the vertex. vertex sides
Example Name the angles you see in the diagram A C D E
Measuring angles with a protractor Different types of angles: Write either <ABC is 32º or m<ABC=32º Acute (less than 90º) Obtuse (more than 90º Right angle (exactly 90º) Straight (180º)
Example Postulate 4: Angle Addition Page 25 in textbook If P is in the interior of <RST, then the measure of <RST is equal to the sum of the measures of <RSP and <PST
Example Given the m<GFJ=155º, find m<GFH and m<HFJ
Example Given that <VRS is a right angle, find m<VRT and m<TRS
Congruent angles 2 angles are congruent if they have the same measure (curved line) <A <B A B
Example Identify all pairs of congruent angles If m<P=120º, what is m<N?
Angle Bisector A ray that divides an angle into 2 angles that are congruent. WY bisects <XWZ
Examples