7-6 Triangles Course 2 Warm Up Problem of the Day Lesson Presentation

an angle that measures less than 90° Course 2 7-6 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 angle of two supplementary angles is 32°. What is the measure of the other angle? hexagon an angle that measures less than 90° 148°

7-6 Triangles Problem of the Day Course 2 7-6 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.

Course 2 7-6 Triangles Learn to classify triangles by their side lengths and angle measures.

Insert Lesson Title Here Course 2 7-6 Triangles Insert Lesson Title Here Vocabulary scalene triangle isosceles triangle equilateral triangle acute triangle obtuse triangle right triangle

Triangles classified by sides Course 2 7-6 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 7-6 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 7-6 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 7-6 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 7-6 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 7-6 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.

Course 2 7-6 Triangles Writing Math When classifying a triangle according to its sides and angles, use the word that describes the sides first, and use the word that describes its angles second.

Additional Example 1A & 1B: Classifying Triangles Course 2 7-6 Triangles Additional Example 1A & 1B: Classifying Triangles Classify each triangle according to its sides and angles. 5 ft A. isosceles Two congruent sides 9 ft 9 ft acute Three acute angles This is an isosceles acute triangle. B. scalene No congruent sides right One right angle 24 m 25 m This is a scalene right triangle. 7 m

Additional Example 1C & 1D: Classifying Triangles Course 2 7-6 Triangles Additional Example 1C & 1D: Classifying Triangles Classify each triangle according to its sides and angles. C. scalene No congruent sides acute Three acute angles This is a scalene acute triangle. D. equilateral Three congruent sides acute Three acute angles This is an equilateral acute triangle.

Insert Lesson Title Here Course 2 7-6 Triangles Insert Lesson Title Here Try This: Example 1A & 1B Classify each triangle according to its sides and angles. 5 ft A. isosceles Two congruent sides 3 ft 3 ft 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 7-6 Triangles Insert Lesson Title Here Try This: Example 1C & 1D 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 7-6 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

Insert Lesson Title Here Course 2 7-6 Triangles Insert Lesson Title Here Try This: Example 2 Identify the different types of triangles in the figure, and determine how many of each there are. A I J B Type How many Name C DJA, JDG HJI, BCD DFE H D Isosceles 5 F G E DJA, ADG 2 Obtuse JDG, JHI, BCD, DEF Acute 4

Insert Lesson Title Here Course 2 7-6 Triangles Insert Lesson Title Here Lesson Quiz Classify each triangle according to its side or angle measures. 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