Chapter 4.1 and 4.2

Classifying Triangles

Angles of Triangles

Concept

Classify Triangles by Angles

A. Classify the triangle as acute, equiangular, obtuse, or right.

Classify Triangles by Angles

B. Classify the triangle as acute, equiangular, obtuse, or right.

Classify Triangles by Angles Within Figures

Classify ΔXYZ as acute, equiangular, obtuse, or right. Explain your reasoning.

Example 2

A. acute

B. equiangular

C. obtuse

D. right

Classify ΔACD as acute, equiangular, obtuse, or right.

Concept

Classify Triangles by Sides Within Figures

If point Y is the midpoint of VX, and WY = 3.0 units, classify ΔVWY as equilateral, isosceles, or scalene. Explain your reasoning.

A. equilateral

B. isosceles

C. scalene

If point C is the midpoint of BD, classify ΔABC as equilateral, isosceles, or scalene.

Finding Missing Values

ALGEBRA Find the measures of the sides of isosceles triangle KLM with base KL.

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ALGEBRA Find x and the measure of each side of equilateral triangle ABC if AB = 6x – 8, BC = 7 + x, and AC = 13 – x.

A. x = 10; all sides are 3.

B. x = 6; all sides are 13.

C. x = 3; all sides are 10.

D. x = 3; all sides are 16.

Prove it!

Example 1 Use the Triangle Angle-Sum Theorem

SOFTBALL The diagram shows the path of the softball in a drill developed by four players. Find the measure of each numbered angle.

Example 1

A. 95

B. 75

C. 57

D. 85

Find the measure of 3.

Concept 3

Example 2 Use the Exterior Angle Theorem

GARDENING Find the measure of FLW in the fenced flower garden shown.

Example 2

A. 30

B. 40

C. 50

D. 130

The piece of quilt fabric is in the shape of a

right triangle. Find the measure of ACD.

Concept 5

Find Angle Measures in Right Triangles

Find the measure of each numbered angle.

A. 50

B. 45

C. 85

D. 130

Find m3.