1. Table of Contents Date: 10/17 Topic: Classifying Triangles
Description: Using sides and angles to classify triangles.
Page: 5

2. Classifying Triangles
Chapter 4 Section 1
Classifying Triangles

3. Classifications of Triangles BY ANGLES
The sides of ∆ABC are
The vertices are points
The angles are

4. Classifications of Triangles BY ANGLES
Acute Triangle
Equiangular Triangle
Obtuse Triangle
Right Triangle

5. Example 1:
a. Classify the triangle as acute, equiangular, obtuse, or right.

6. Example 1:
b. Classify the triangle as acute, equiangular, obtuse, or right.

7. Example 2:
Classify ∆XYZ as acute, equiangular, obtuse, or right. Explain your reasoning.

8. Classifications of Triangles BY SIDES
Equilateral Triangle
Isosceles Triangle
Scalene Triangle

9. Example 3:
If point Y is the midpoint of and WY = 3.0 units, classify ∆VWY as equilateral, isosceles, or scalene. Explain your reasoning.

10. Example 4:
a) Find the measures of the sides of isosceles triangle KLM with base KL

11. Example 4:
b) Find the value of x and the measures of each side of an equilateral triangle ABC if
AB = 6x – 8, BC = 7 + x, and AC = 13 – x.

12. Summary!

13. Summary!

14. Summary!
1. Name the vertices of the equilateral triangle.

15. Summary!
2. Classify ∆ABC by its sides and angles.

16. Summary!
Multiple Choice Which statement is not true? a) In an isosceles triangle, the base is congruent to one of the legs. b) A triangle cannot be scalene and isosceles. c) A triangle cannot be obtuse and contain a 90° angle. d) A triangle can be obtuse and isosceles.

17. Summary!
4. Classify ∆LMN as acute, equiangular, obtuse, or right.

18. Summary!
5. Triangle RST is isosceles with ∠S as the vertex angle. If ST = 3x – 11, SR = x + 3, and RT = x – 2, find RT.