Classifying Triangles

Classifying Triangles

Learning Targets:

Classify Triangles by Angles

Classify Triangles by Sides

Classifying Triangles by Angles and Sides

The next slide is a video by Khan Academy that describes how to categorize triangles by angles and sides.

Take notes from this video in your personal notebook.

Kahn Academy Classifying Triangles

Classify Triangles by Angles and Sides Video

The next slide is a video by Math Antics that describes how to categorize triangles by angles and sides. This video has additional insight that Khan didn't mentioned.

Watch video, then take notes in your personal notebook.

Classify by Angles -Acute

 $A\ triangle\ with\ each\ angle$     $being\ less\ than\ 90\degree$                                 

 $\Delta ABC\ \ is\ an\ acute\ triangle$  

Classify by Angles - Right Triangle

• One right angle

• The other two angles will be acute

•  $\Delta ABC\ is\ a\ right\ triangle$  

Classify by Angles - Obtuse

•  $One\ Angle\ is\ greater\ than\ 90\degree$  

•  $The\ other\ two\ angles\ will\$   $be\ acute\ angles$  

Classify by Sides - Scalene

• Triangle has no congruent sides

• The measure of the sides are not equal (definition of congruent segments)

•  $AB\ne BC\ne AC$  

Classify by Sides - Isosceles

• At least two sides of triangle are congruent.

•  $GK\cong HK$  since,  $GK=4.19=HK$  

Classify by Sides - Equilateral

•  Has three congruent sides

•  $DE\cong EF\cong DF$  since  $DE=EF=DF$  

• Each angle in an equilateral triangle are congruent and are  $60\degree$ 

Classify triangle by angles and sides. Classify by angle then side.

• One angle is greater than  $90\degree.$   $m\angle K=114\degree$ so triangle is obtuse

• Two sides of triangle are congruent, so triangle is isosceles. 

• Triangle is classified as Obtuse - Isosceles.

Multiple Choice

Classify the triangle by angle and side.

• Acute - Scalene

• Obtuse - Scalene

• scalene -isosceles

• Obtuse-isosceles

Multiple Choice

• Acute - Isosceles

• Right - Scalene

• Right - Isosceles

• Isosceles - Equilateral

Multiple Choice

Classify the triangle by angle and side.

• Acute - isosceles

• Obtuse - Scalene

• isosceles-acute

• Obtuse-isosceles

Multiple Choice

Classify the triangle by angle and side.

• Obtuse-isosceles

• Right-isosceles

• Acute - equilateral

• Acute - right

Multiple Choice

Classify triangle by angle and side.

• Obtuse - Isosceles

• Acute - Isosceles

• Right - Equilateral

• Acute - Equilateral