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Lesson 9.2 Angle Relationships and Parallel Lines. . Types of Angles. Acute -. Obtuse - . Angles that measure less than 90. Angles that measure more than 90 and less than 180. Right -. Angles that measure exactly 90. Adjacent Angles.
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Types of Angles Acute - Obtuse - Angles that measure less than 90. Angles that measure more than 90 and less than 180. Right - Angles that measure exactly 90.
Adjacent Angles • Share a vertex and a side but no points in the interiors. <AXB and <BXC are adjacent angles B A <AXC and <BXC are not adjacent angles Why? X C
Complementary Angles - Angles whose sum is 90 . a b Complementary angles do not have to be adjacent. x y
Supplementary Angles - Angles whose sum is 180 . k t Supplementary angles do not have to be adjacent. b c
Congruent Angles • Angles that have the same measurement • Notation:
Vertical Angles - Opposite angles that are formed by intersecting lines. a Opposite angles (vertical angles) are ALWAYScongruent. b
Identifying Corresponding Angles Transversal -A line that intersects two other lines.
Identifying Corresponding Angles Corresponding Angles - Two angles that are formed by two lines and a transversal and occupy corresponding positions. A B 1 2 3 4 5 6 7 8 C D Corresponding Angles If the two lines are parallel, then the corresponding angles are congruent.
Identifying Alternate Interior Angles Alternate Interior Angles: -interior of a pair of lines on opposite sides of the transversal. A B 1 2 3 4 5 6 7 8 C D Corresponding Angles If the two lines are parallel, then the alternate interior angles are congruent.
Find the value of n. 1) 2)
Homework • Page 452 -453 (1-11 all and 13) • Draw figures in the homework