Classifying Polygons

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Lesson Objective: The student will be able to identify a variety of polygons.

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Created by Joshua Gillman

Engage

Classifying Polygons (Emerging)

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A polygon's sides must be what?

1. Curved
2. Even numbered
3. Straight
4. Odd numbered

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Engage

Classifying Polygons (Intermediate)

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Which of the following is NOT a polygon?

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1. Brick
2. Window
3. Donut
4. Stop sign

Engage

Classifying Polygons (Advanced)

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What is the name of the polygon pictured below?

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1. Decagon
2. Heptagon
3. Dodecagon
4. Octagon

Engage

We are going to watch the following video to learn more about polygons.

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Classifying Polygons

Explain

Classifying Polygons

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What is a polygon?:

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A polygon is a closed figure made of line segments. Polygons have at least 3 angles and at least 3 straight line segments. A polygon is named by the number of sides it has.

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Explain

Classifying Polygons

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How Do I Calculate The Measure of An Angle in A Polygon?:

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The formula for finding the sum of the measure of the interior angles is (n - 2) * 180. To find the measure of one interior angle, we take that formula and divide by the number of sides (n):

(n - 2) * 180 / n.

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Explain

Classifying Polygons

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Convex Polygon or Concave Polygon:

• A Polygon is Convex if no line that contains a side of the polygon contains a point in the interior of the polygon. Every interior angle in a convex polygon is less than 180°.
• A polygon that is not convex is called non convex or Concave.

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Explain

Classifying Polygons

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Examples of Convex Polygon and Concave Polygon:

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Explain

Classifying Polygons

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Commonly Used Polygons:

a. In an Equilateral Polygon, all sides are congruent.

b. In an Equiangular Polygon, all angles in the interior of the polygon are congruent.

c. A Regular Polygon is a convex polygon that is both equilateral and equiangular.

d. Irregular Polygon is one that does not have all sides equal and all angles equal.

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Explain

Classifying Polygons

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The illustration gives examples on how to classify a polygon by the number of sides and whether the polygon is equilateral, equiangular, or regular.

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Explore

Classifying Polygons

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• Your next step is to do complete an assignment independently.
• Remember that if you get stuck on a question look back at this presentation to help you.

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Explore

Classifying Polygons (Emerging)

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Now you will work on an assignment as your independent practice. Click on the picture to access the assignment.

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Explore

Classifying Polygons (Intermediate)

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Now you will work on an assignment as your independent practice. Click on the picture to access the assignment.

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Explore

Classifying Polygons (Advanced)

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Now you will work on an assignment as your independent practice. Click on the picture to access the assignment.

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Apply and Reflect

Classifying Polygons (Emerging)

Which image represents a polygon?

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1. b. C. d.

Apply and Reflect

Classifying Polygons (Intermediate)

Which Polygon Is Equilateral and Equiangular?:

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1. b. c. d.

Apply and Reflect

Classifying Polygons (Intermediate)

What is the measure of each angle in the polygon pictured below?:

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1. 55
2. 1,440
3. 90
4. 144