Classifying Triangles by Their Side Lengths

What are the two ways to classify triangles?

• By the angles and number of sides

• By the angles and side lengths

• By the side lengths and the size of the triangle

• By the angles and the how many points

A triangle can be classified as an isosceles triangle if there are two equal sides.

• True

• False

What does the term scalene mean?

• all sides equal

• two sides equal

• 90 degree angle

• all sides not equal

Identify the triangle by its sides

• Isosceles

• Equilateral

• Scalene

Which triangle is an scalene triangle?

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Which type of triangle is pictured?

• Equilateral

• Isosceles

• Scalene

Match the following definitions to the correct vocabulary term.

• A triangle with only 2 congruent sides.

• Scalene Triangle

• A triangle that has no equal sides.

• Equilateral Triangle

• A triangle that has all congruent sides.

• Isosceles Triangle

The triangles have been classified by a shared attribute (side length or angle type). Use one of the words acute, right, obtuse, scalene, isosceles, or equilateral to label the headings to identify the way the triangles have been sorted.

c

b

d

Obtuse

Acute

Equilateral

Isosceles

Right

Scalene

Which figures belong in the part of the organizer labeled "Isosceles triangles"?

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Triangles can be classified in 2 ways:

By their angles: acute, right, or obtuse

By their sides: equilateral, isosceles, scalene

Select all the ways the triangle can be classified.

• Acute

• Scalene

• Obtuse

• Equilateral

• Isosceles