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# 8-6 - PowerPoint PPT Presentation

8-6. Classifying Triangles. Course 2. Warm Up. Problem of the Day. Lesson Presentation. 8-6. Classifying Triangles. Course 2. Warm Up 1. What is the name of a six-sided figure? 2. What is the definition of an acute angle?

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Presentation Transcript

Classifying Triangles

Course 2

Warm Up

Problem of the Day

Lesson Presentation

Classifying Triangles

Course 2

Warm Up

1.What is the name of a six-sided figure?

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°

Classifying Triangles

Course 2

Problem of the Day

Use 6 congruent line segments to form 4 equilateral triangles. (Hint: Use toothpicks or other objects to make a three-dimensional model with the segments.)

Place the segments so they form a pyramid.

Classifying Triangles

Course 2

Learn to classify triangles by their side lengths and angle measures.

Classifying Triangles

Course 2

Insert Lesson Title Here

Vocabulary

scalene triangle

isosceles triangle

equilateral triangle

acute triangle

obtuse triangle

right triangle

Classifying Triangles

Course 2

One way to classify triangles is by the lengths of their sides.

Triangles classified by sides

A scalene triangle

has no congruent sides.

Classifying Triangles

Course 2

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

Classifying Triangles

Course 2

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.

Classifying Triangles

Course 2

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.

Classifying Triangles

Course 2

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 trianglehas

one obtuse angle.

Classifying Triangles

Course 2

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 one right angle.

Classifying Triangles

Course 2

Classify each triangle according to its sides and angles.

Two congruent sides

A.

isosceles

acute

Three acute angles

This is an isosceles acute triangle.

B.

scalene

No congruent sides

right

One right angle

This is a scalene right triangle.

Classifying Triangles

Course 2

Classify each triangle according to its sides and angles.

equilateral

Three congruent sides

C.

acute

Three acute angles

This is a equilateral acute triangle.

D.

scalene

No congruent sides

right

One right angle

This is a scalene right triangle.

Classifying Triangles

Course 2

Insert Lesson Title Here

Check It Out: Example 1

Classify each triangle according to its sides and angles.

isosceles

Two congruent sides

A.

obtuse

One obtuse angle

This is an isosceles obtuse triangle.

Two congruent sides

B.

isosceles

right

One right angle

This is an isosceles right triangle.

Classifying Triangles

Course 2

Insert Lesson Title Here

Check It Out: Example 1

Classify each triangle according to its sides and angles.

scalene

No congruent sides

C.

obtuse

One angle exceeding 90°

This is a scalene obtuse triangle.

scalene

D.

No congruent sides

obtuse

One angle exceeding 90°

This is a scalene obtuse triangle.

Classifying Triangles

Course 2

Identify the different types of triangles in the figure, and determine how many of each there are.

2

Scalene

ABD,

BCD

2

Isosceles

ACE,

ABC

Right

2

ABD,

BCD

1

Obtuse

ACE

1

Acute

ABC

Classifying Triangles

DJA,

JDG

HJI,

BCD

DFE

DJA,

JDG,

JHI,

BCD,

DEF

Course 2

Insert Lesson Title Here

Check It Out: Example 2

Identify the different types of triangles in the figure, and determine how many of each there are.

A

B

I

Type

How many

Name

J

C

D

H

Isosceles

5

F

G

E

2

Obtuse

Acute

4

Classifying Triangles

Course 2

Insert Lesson Title Here

Lesson Quiz

Classify each triangle according to its sides and angles.

1. 7ft, 8ft, 12ft

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.

scalene

right

isosceles

obtuse

1 isosceles acute triangle, 1 equilateral triangle, 1 scalene right triangle