Types of TriangleChapter 3.6Chapter 3.6

Objective- name the various types of triangles and their

parts.

Triangles by sides:

Scalene- a scalene triangle is triangle in which no two sides are

congruentW

A

D

G

U M

Isosceles-an isosceles triangle is a triangle in which at least 2 sides are congruent

Equilateral- an equilateral triangle is a triangle in which all sides are congruent Y

U M

Triangles by angles:

Acute: An acute triangle is a triangle in which all angles are acute and add up to 180 degrees.

80

4060R

D

E

Right: A right triangle is a triangle in which one of the angles is a right angle.H

OT

Obtuse: An obtuse triangle is a triangle in which ONE of the angles is an obtuse angle.

F

IN110

40

30

D

CB

A

Given: AD and CD are legs of isosceles ADC. B is the midpoint of AC

Prove: A C

1. AD and CD are legs of isosceles ADC.

2. AD CD

3. B is midpt. of AC4. AB BC

5. Draw DB6. DB DB7. DAB DCB8. A C

1. Given

2. An isos. triangle is a triangle in which at least 2 sides are .

3. Given4. A mdpt. divides a seg into 2

segs.5. 2 points determine a line.6. Reflexive Property7. SSS8. CPCTC

CB

A Given: AB = x + 3 AC = 3x + 2 BC = 2x + 3 Perimeter of ABC = 20

Show that ABC is scalene.

Perimeter = 20 = x + 3 + 3x + 2 + 2x + 320 = 6x + 812 = 6x2 = x

AB = 2 + 3 = 5

AC = 3(2) + 2 = 8

BC = 2(2) + 3 = 7

ABC is scalene because no sides are .