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9-4 Triangles. Vocabulary:. Line Segment: The part of a line that has 2 endpoints. BOARD! Triangle: 3 line segments that intersect only at their endpoints. BOARD!. The sum of the angles of a triangle is 180 degrees. Example on board:. Use ratios to find angle measures:.
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Vocabulary: • Line Segment: The part of a line that has 2 endpoints. • BOARD! • Triangle: 3 line segments that intersect only at their endpoints. • BOARD!
The sum of the angles of a triangle is 180 degrees. • Example on board:
Use ratios to find angle measures: • If the angles are in a ratio of 2 : 3 : 5, then you make the equation 2x + 3x + 5x = 180 Now solve: 2x + 3x + 5x = 180 10x = 180 10 10 x = 18
Use the ratio to find the angle measures: • x = 18 • 2x = 2 · 18 = 36 • 3x = 3 · 18 = 54 • 5x = 5 · 18 = 90 180
Classifying Triangles: • By sides: Scalene: no equal sides Isosceles: 2 congruent sides Equilateral: all sides congruent
Classifying Triangles: • By angles: • Acute: all angles acute • Right: one right angle • Obtuse: one obtuse angle: an angle greater than 90 degrees
Homework: • 9-4 Practice handout # 1-16