GeometrySection 1.4

Measure and classify Angles

Terms

• Angle consists of two different rays with the same endpoint

vertexside

• To name angles, either name with 3 points (point at the vertex in the middle), or name with the vertex point.•See mimio example

• To measure use protractor•See mimio example

Classifying angles

• Acute angle measures more than 0 degrees, but less than 90 degrees

• Right angle measures 90 degrees• Obtuse angle measures more than

90 degrees but less than 180 degrees• Straight angle measures 180

degrees

Angle Addition Postulate

• If P is in the interior of angle RST, then the measure of angle RST is equal to the sum of angle PST and angle RST•See mimio example

Examples

• Page 29•Problems #23, 25

Terms

• Two angles are congruent if they have the same measure

• Angle bisector is a ray that divides an angle into two angles that are congruent

Examples

• Page 30 • Problem 41

Assignment

• Section 1.4• Page 28• Problems # 4, 8 – 40 even, 56 - 60