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WHAT MAKES A TRIANGLE A TRIANGLE?

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STOP. DROP. ASSESS YOURSELF!Essential Question: How are triangles classified?

Level 4- I am able to determine all attributes that classify a triangle and can identify a triangle by more than one attribute.

Level 3- I am able to determine some attributes of a triangle and can identify some triangles.

Level 2- With help, I can identify all attributes that classify a triangle and can identify a triangle by more than one attribute.

Level 1- Even with help, I am unable to identify the attributes that classify a triangle.

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They all have:

3 Sides3 Vertices*** The point where two line segments

meet 3 Angles

WHAT DO ALL TRIANGLES HAVE IN COMMON?

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HOW ARE TRIANGLES CLASSIFIED?

Triangles are classified by:

Measure of the angles

Length of the sides

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MEASURE OF ANGLES Acute Triangle- All angles measure less

than 90 degrees. Right Triangle- One angle measures 90

degrees. Obtuse Triangle-The measure of one

angle is greater than 90 degrees.

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ACUTE TRIANGLE

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RIGHT TRIANGLE

Right Triangles are classified by a square. This lets you know that the angle is equal to 90 degrees.

90 degrees looks like a “L” or a backwards “L”

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OBTUSE TRIANGLE

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LENGTH OF SIDES Equilateral Triangle- All sides have the

same length. Isosceles Triangle- 2 sides have the

same length. Scalene Triangle- No sides have the

same length.

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EQUILATERAL TRIANGLE

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ISOSCELES TRIANGLE

The lines on the sides of the triangles let you know that they are congruent. Congruent means same size and same shape.

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SCALENE TRIANGLE

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TURN AND TALKH.O.T. (Higher Order Thinking) Question:

Can a triangle be classified by its length and the measure of its angles? How do you know?

Draw a picture to help you figure it out.

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TRIANGLE SORT

Length Measure of the Angles

Acute Right Obtuse

Equilateral

Isosceles

Scalene

Directions: Look at where the length and measures of angles intersect. Draw a triangle that fits both descriptions.

** If a triangle does NOT fit BOTH descriptions, leave the spot blank.

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ASSESS YOURSELF! After learning this lesson I feel as though I am a Level….Essential Question: How are triangles classified?

Level 4- I am able to determine all attributes that classify a triangle and can identify a triangle by more than one attribute.

Level 3- I am able to determine some attributes of a triangle and can identify some triangles.

Level 2- With help, I can identify all attributes that classify a triangle and can identify a triangle by more than one attribute.

Level 1- Even with help, I am unable to identify the attributes that classify a triangle.

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Length of the sides Measure of the angles

Acute Triangle Right Triangle Obtuse TriangleEquilateral Triangle

Isosceles Triangle

Scalene Triangle