8-6 Classifying Triangles Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes

8-6 Classifying Triangles Warm Up 1. What is the name of a six-sided figure? 2. What is the definition of an acute angle? 3. The measure of one of two supplementary angles is 32°. What is the measure of the other angle? hexagon an angle that measures less than 90° 148°

8-6 Classifying Triangles Problem of the Day Use 6 congruent line segments to form 4 equilateral triangles. (Hint: Use toothpicks or other objects to model the segments.) Place the segments so they form a pyramid.

8-6 Classifying Triangles Learn to classify triangles by their side lengths and angle measures.

8-6 Classifying Triangles Vocabulary scalene triangle isosceles triangle equilateral triangle acute triangle obtuse triangle right triangle

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Triangles classified by sides A scalene triangle has no congruent sides.

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Triangles classified by sides An isosceles triangle has at least 2 congruent sides

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Triangles classified by sides In an equilateral triangle, all of the sides are congruent.

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Another way is by the measures of their angles. Triangles classified by angles In an acute triangle, all of the angles are acute.

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Another way is by the measures of their angles. Triangles classified by angles An obtuse triangle has one obtuse angle.

8-6 Classifying Triangles One way to classify triangles is by the lengths of their sides. Another way is by the measures of their angles. Triangles classified by angles A right triangle has one right angle.

8-6 Classifying Triangles Classify each triangle according to its sides and angles. Additional Example 1: Classifying Triangles A. Two congruent sides acuteThree acute angles This is an isosceles acute triangle. B. No congruent sides rightOne right angle This is a scalene right triangle. isosceles scalene

8-6 Classifying Triangles Classify each triangle according to its sides and angles. Additional Example 1: Classifying Triangles C. Three congruent sides acuteThree acute angles This is an equilateral acute triangle. D.No congruent sides rightOne right angle This is a scalene right triangle. equilateral scalene

8-6 Classifying Triangles Check It Out: Example 1 Classify each triangle according to its sides and angles. A. Two congruent sides acuteOne obtuse angle This is an isosceles acute triangle. B. Two congruent sides rightOne right angle This is an isosceles right triangle. isosceles

8-6 Classifying Triangles Check It Out: Example 1 Classify each triangle according to its sides and angles. C. No congruent sides obtuse One angle exceeding 90° This is a scalene obtuse triangle. D.No congruent sides obtuseOne angle exceeding 90° This is a scalene obtuse triangle. scalene

8-6 Classifying Triangles Identify the different types of triangles in the figure, and determine how many of each there are. Additional Example 2: Identifying Triangles NameHow manyType Scalene 2 ABD,BCD Isosceles Right Obtuse Acute ACE, ABC ABD,BCD ACE ABC

8-6 Classifying Triangles Check It Out: Example 2 A B C D E F G H I J Identify the different types of triangles in the figure, and determine how many of each there are. Isosceles Obtuse Acute NameHow manyType DJA,JDG HJI,BCD DFE DJA,ADG JDG,JHI, BCD,DEF

8-6 Classifying Triangles Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

8-6 Classifying Triangles Lesson Quiz Classify each triangle according to its sides and angles ft, 8 ft, 12 ft 2. 45°, 90°, 45° 3. 12, 9, °, 20°, 40° 5. Identify the different types of triangles in the figure and determine how many of each there are. right scalene isosceles obtuse 1 isosceles acute triangle, 1 equilateral triangle, 1 scalene right triangle

8-6 Classifying Triangles 1. Classify the triangle according to its sides. 9 ft, 16 ft, 9 ft A. equilateral B. isosceles C. scalene D. right Lesson Quiz for Student Response Systems

8-6 Classifying Triangles 2. Classify the triangle according to its sides. 5 in., 8 in., 12 in. A. equilateral B. isosceles C. scalene D. right Lesson Quiz for Student Response Systems

8-6 Classifying Triangles 3. Classify the triangle according to its angles. 45°, 105°, 30° A. acute B. obtuse C. right D. equilateral Lesson Quiz for Student Response Systems

8-6 Classifying Triangles 4. Classify the triangle according to its angles. 27°, 90°, 63° A. acute B. obtuse C. right D. equilateral Lesson Quiz for Student Response Systems