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Section 4.1 Classifying Triangles. Geometry. Triangle – 3-sided polygon named using its 3 vertices Triangles are classified in two ways: sides and angles . Angle Classifications. All triangles have at least 2 acute angles, the third is used to classify the angle.
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Section 4.1 Classifying Triangles Geometry
Triangle – 3-sided polygon named using its 3 vertices • Triangles are classified in two ways: sides and angles.
Angle Classifications • All triangles have at least 2 acute angles, the third is used to classify the angle. • Acute triangle - 3 acute angles • Equiangular triangle – 3 congruent acute angles • Obtuse triangle - 1 obtuse angle • Right triangle - 1 right angle
Example 1 • Classify each triangle as acute, equiangular, obtuse, or right. A. C. 101° B. 40° 60° 60° 60° D. 70° 90° 70°
Side Classifications • Triangles are also classified by the number of congruent sides they have. • Equilateral triangle - 3 congruent sides • Isosceles triangle – at least 2 congruent sides • Scalene triangle – no congruent sides
Example 2 • Classify each triangle equilateral, isosceles, or scalene. 60° 8 in 8 in 60° 60° 10 ft 6 ft 8 ft 4 in
Isosceles Triangles Leg Leg Base
Example 3 M Find the measures of the 3 sides of isosceles triangle KLM with base KL. 4x - 13 12 - x K L x + 6
Homework • Page 239: 15-43 all