How do you measure, name and classify angles? What is the Angle Addition Postulate? How do you identify angle pairs? Chapter 1 Section 1.6

Warm up In your books, page 36, 1-6 at very top

Angles A figure formed by two rays that have the same endpoint. The two rays are called the sides of the angle The common endpoint is called the vertex. Can be named as B, ABC or 1 I prefer ABC or 1 Make sure that the vertex is the middle point. A B C 1

Angle Classification Acute Angle – an angle measuring between 0 and 90 degrees Right Angle – an angle measuring 90 degrees Obtuse Angle – an angle measuring between 90 to 180 degrees Straight Angle – an angle measuring 180 degrees

Classify these angles

Congruent Angles Angles with the same measure

Challenge! You and your partner figure out how many angles there are

Postulate 1-8: Angle Addition Postulate If point B lies in the interior of AOC, then m AOB + m BOC =m AOC If AOC is a straight angle and B is any point not on line AC, then m AOB + m BOC =180 B C OA O A C B

Example The measure of angle AOB is x and the measure of angle BOC is x+3. The measure of angle AOC is 55 degrees. What is angle AOB and angle BOC? C B A O

Special Angle Pairs Vertical Angles Adjacent Angles – common side, common vertex, no common interior points Complimentary Angles – two angles whose measures add up to 90 Supplementary Angles – two angles whose measures add up to 180

Adjacent Angles ADJACENT NOT ADJACENT

Example - Identifying Angle Pairs In the diagram below, identify all types of the following: ComplementarySupplementaryVertical

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