Classifying triangles mary marks

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Classifying Triangles

Mary S. Marks

Objective

• Today we will classify triangles by their sides and their angles.

• Given two angles in a triangle, we will find the third angle.

What are triangles?

• Tell me what you know about triangles.

(Note to teacher: Ask students what they know about triangles. Students should come up three sides, three angles, three vertices.)

Classifying Triangles by their Sides

• Equilateral Triangles - all sides are congruent

• Isosceles Triangles - two sides are congruent

• Scalene Triangles - no sides are congruent

Classifying Triangles by their Angles

• Acute Triangles - have three acute angles

• Obtuse Triangles - have one obtuse angle

• Right Triangles - have one right angle

Examples of triangles

Sum of the measures of the angles in a triangle

• What type of angle do the angles in the triangle form?

• How many degrees does this type of angle have?

•How many degrees does this type of angle have?

Finding the missing angle

• Two angles are given, find the measurement of the third angle

What is a triangle?

Equilateral

Isosceles

Triangles in the Real World

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