an angle that measures less than 90° Course 2 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°

Classifying Triangles Course 2 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 make a three-dimensional model with the segments.) Place the segments so they form a pyramid.

Classifying Triangles Course 2 8-6 Classifying Triangles Learn to classify triangles by their side lengths and angle measures.

Insert Lesson Title Here Course 2 8-6 Classifying Triangles Insert Lesson Title Here Vocabulary scalene triangle isosceles triangle equilateral triangle acute triangle obtuse triangle right triangle

Triangles classified by sides Course 2 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.

Triangles classified by sides Course 2 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

Triangles classified by sides Course 2 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.

Triangles classified by angles Course 2 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.

Triangles classified by angles Course 2 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.

Triangles classified by angles Course 2 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.

Additional Example 1: Classifying Triangles Course 2 8-6 Classifying Triangles Additional Example 1: Classifying Triangles Classify each triangle according to its sides and angles. A. isosceles Two congruent sides acute Three acute angles This is an isosceles acute triangle. B. scalene No congruent sides right One right angle This is a scalene right triangle.

Additional Example 1: Classifying Triangles Course 2 8-6 Classifying Triangles Additional Example 1: Classifying Triangles Classify each triangle according to its sides and angles. C. equilateral Three congruent sides acute Three acute angles This is a equilateral acute triangle. D. scalene No congruent sides right One right angle This is a scalene right triangle.

Insert Lesson Title Here Course 2 8-6 Classifying Triangles Insert Lesson Title Here Check It Out: Example 1 Classify each triangle according to its sides and angles. A. isosceles Two congruent sides obtuse One obtuse angle This is an isosceles obtuse triangle. B. isosceles Two congruent sides right One right angle This is an isosceles right triangle.

Insert Lesson Title Here Course 2 8-6 Classifying Triangles Insert Lesson Title Here Check It Out: Example 1 Classify each triangle according to its sides and angles. C. scalene No congruent sides obtuse One angle exceeding 90° This is a scalene obtuse triangle. D. scalene No congruent sides obtuse One angle exceeding 90° This is a scalene obtuse triangle.

Additional Example 2: Identifying Triangles Course 2 8-6 Classifying Triangles Additional Example 2: Identifying Triangles Identify the different types of triangles in the figure, and determine how many of each there are. Type How many Name Scalene 2 ABD, BCD Isosceles 2 ACE, ABC Right 2 ABD, BCD Obtuse 1 ACE Acute 1 ABC

Classifying Triangles Insert Lesson Title Here Course 2 8-6 Classifying Triangles Insert Lesson Title Here Lesson Quiz Classify each triangle according to its sides and angles. 1. 7ft, 8ft, 12ft 2. 45°, 90°, 45° 3. 12, 9, 12 4. 120°, 20°, 40° 5. Identify the different types of triangles in the figure and determine how many of each there are. scalene right isosceles obtuse 1 isosceles acute triangle, 1 equilateral triangle, 1 scalene right triangle