1. Holt CA Course 1 9-6 Classifying Triangles Warm Up Warm Up California Standards California Standards Lesson Presentation Lesson PresentationPreview

2. Holt CA Course 1 9-6 Classifying Triangles Warm Up 1. What is the name of a six-sided polygon? 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°

3. Holt CA Course 1 9-6 Classifying Triangles Preparation for MG2.3 Draw quadrilaterals and triangles from given information about them (e.g., a quadrilateral having equal sides but no right angles, a right isosceles triangle.) California Standards

4. Holt CA Course 1 9-6 Classifying Triangles Vocabulary scalene triangle isosceles triangle equilateral triangle acute triangle obtuse triangle right triangle

5. Holt CA Course 1 9-6 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.

6. Holt CA Course 1 9-6 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.

7. Holt CA Course 1 9-6 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. Holt CA Course 1 9-6 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.

9. Holt CA Course 1 9-6 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.

10. Holt CA Course 1 9-6 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 exactly one right angle.

11. Holt CA Course 1 9-6 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

12. Holt CA Course 1 9-6 Classifying Triangles Identify the different types of triangles in the figure, and determine how many of each there are. Additional Example 2: Identifying Triangles TypeHow manyName Scalene 2 ABD,CBD Isosceles Right Obtuse Acute ACE, ABC ABD,CBD ACE ABC 2 2 1 1

13. Holt CA Course 1 9-6 Classifying Triangles Check It Out! Example 1 Classify each triangle according to its sides and angles. A. Two congruent sides obtuseOne obtuse angle This is an isosceles obtuse triangle. B. Two congruent sides rightOne right angle This is an isosceles right triangle. isosceles

14. Holt CA Course 1 9-6 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 5 2 4 NameHow manyType DJA,JDG HJI,BCD DFE DJA,ADG JDG,JHI, BCD,DEF

15. Holt CA Course 1 9-6 Classifying Triangles Lesson Quiz Classify each triangle according to its sides or angles. 1. 7 ft, 8 ft, 12 ft 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. right scalene isosceles obtuse 1 isosceles acute triangle, 1 equilateral triangle, 1 scalene right triangle

16. Holt CA Course 1 9-6 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

17. Holt CA Course 1 9-6 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