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GHSGT Review. Lines and Angles. Lines. A line has two arrows to show that it goes on forever A line segment has two endpoints to show that it stops on both sides Lines that do not intersect are called parallel lines Lines that intersect by forming a right angle are perpendicular.
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GHSGT Review Lines and Angles
Lines • A line has two arrows to show that it goes on forever • A line segment has two endpoints to show that it stops on both sides • Lines that do not intersect are called parallel lines • Lines that intersect by forming a right angle are perpendicular
Angle Vocab • A ray has one endpoint and one arrow to show that it goes on forever in only one direction • Two ray can join to form an angle. The point where they join is called the vertex of the angle. Each ray is called a side of the angle. vertex
Types of Angles • An acute angle has measure less than 90⁰ • All right angles have measure equal to 90⁰ • An obtuse angle has measure greater than 90⁰ • A straight angle has measure of exactly 180⁰
Angle Relationships • Adjacent angles share a side: • Complementary angles add up to 90⁰ • Supplementary angles add up to 180⁰ C A D B E F G H J K
Transversals • If two parallel lines are intersected, that line is called the transversal • Eight angles are formed: four are acute, and four are obtuse. The four acute angles are congruent to each other, and the four obtuse angles are congruent to each other. • Each pair of acute and obtuse angles are supplementary, so they have a sum of 180⁰
1. Sarah’s yard and her neighbor’s yard form complementary angles. What is the sum of the degree of measures of the two yards? • A. 80⁰ • B. 90⁰ • C. 120⁰ • D. 180⁰
2. Two streets in Josh’s neighborhood run next to each other in the same direction but do not intersect. These streets are an example of what kind of lines? • A. perpendicular • B. adjacent • C. supplementary • D. parallel
3. The lines in the symbol below are examples of what kind of line segments? • A. parallel • B. collinear • C. angles • D. perpendicular
4. Two lines are parallel and intersected by a transversal. If the measure of angle 1 is 50⁰, find the measure of angle 2. • A. 50 • B. 100 • C. 130 • D. 180 1 2
Solutions • 1. B – The sum of complementary angles is 90 degrees. • 2. D – Lines that do not intersect are parallel. • 3. D – These line segment appear to be intersecting at right angles. • 4. A – Both angles are acute, so in this scenario they must have equal measures.