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SECTION 1-5. Exploring Angle Pairs. OBJECTIVE. To identify special angle pairs and use their relationships to find angle measures. VOCABULARY. Adjacent Angles – two coplanar angles with a common side, a common vertex, and no common interior points. 1 and 2 3 and 4. 3. 4. 1. 2.
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SECTION 1-5 Exploring Angle Pairs
OBJECTIVE To identify special angle pairs and use their relationships to find angle measures
VOCABULARY Adjacent Angles – two coplanar angles with a common side, a common vertex, and no common interior points. 1 and 2 3 and 4 3 4 1 2
VOCABULARY Vertical angles – two angles whose sides are opposite rays (formed by the intersection of two lines). 3 1 and 2 3 and 4 1 2 4
VOCABULARY Complementary angles – two angles whose measures have a sum of 90˚. Each angle is called the complement of the other. 43˚ 1 and 2 A and B A 1 47˚ 2 B
VOCABULARY Supplementary angles – two angles whose measures have a sum of 180˚. Each angle is called the supplement of the other. 160˚ 20˚ B 1 and 2 A and B A 1 2
CLASS WORK Use the diagram at the right. Is each statement true? Explain. 1. 2 and 5 are adjacent angles. 2. 1 and 4 are vertical angles. 3. 4 and 5 are complementary.
CLASS WORK Name an angle or angles in the diagram described by each of the following. 4. complementary to BOC 5. supplementary to DOB 6. adjacent and supplementary to AOC
VOCABULARY Linear pair – pair of adjacent angles whose non-common sides are opposite rays. The angles of a linear pair form a straight angle. D ABD and DBC A B C
KEY CONCEPT D A B C
VOCABULARY Angle bisector – ray that divides an angle into two congruent angles. OB is the angle bisector of AOC B A C O
CLASS WORK 7. Algebra In the diagram, XY bisects WXZ. a. Solve for x and find mWXY. b. Find mYXZ. c. Find mWXZ.
COMPARE AND CONTRAST Relationships you can assume true without marks: Relationships that must be marked: • Angles are adjacent. • Angles are adjacent supplementary (form a line). • Angles are vertical angles. • Angles or segments are congruent. • An angle is a right angle. • Angles are complementary.
Summary Angles pairs with special totals: Complementary angles sum to be 90°. Supplementary angles sum to be 180°. Angle pairs formed by intersecting lines. Adjacent angles are a linear pair that sum to be 180 °. Opposite angles are vertical angles that are congruent.
EXIT PROBLEM In the diagram at the right, mHKI =48. Find each of the following. mHKJ mIKJ mFKG mFKJ