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Table of Contents
Date: 10/17
Topic: Classifying Triangles
Description: Using sides and angles to classify
triangles.
Page: 5
Chapter 4 Section 1
Classifying Triangles
Classifications of Triangles
BY ANGLES
The sides of ∆ABC are
The vertices are points
The angles are
Classifications of Triangles
BY ANGLES
Acute Triangle
Equiangular
Triangle
Obtuse Triangle
Right Triangle
Example 1:
a. Classify the triangle as acute, equiangular,
obtuse, or right.
Example 1:
b. Classify the triangle as acute, equiangular,
obtuse, or right.
Example 2:
Classify ∆XYZ as acute, equiangular, obtuse, or
right. Explain your reasoning.
Classifications of Triangles
BY SIDES
Equilateral Triangle
Isosceles Triangle
Scalene Triangle
Example 3:
If point Y is the midpoint of and WY = 3.0 units,
classify ∆VWY as equilateral, isosceles, or
scalene. Explain your reasoning.
Example 4:
a) Find the measures of the sides of isosceles
triangle KLM with base KL
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.
Summary!
Summary!
Summary!
1. Name the vertices of the equilateral triangle.
Summary!
2. Classify ∆ABC by its sides and angles.
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.
Summary!
4. Classify ∆LMN as acute, equiangular, obtuse,
or right.
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.