Intro to Polygons

Intro to Polygons

Leanring Intention

Success Criteria

We will name and classify 2-dimensional polygons based on their sides, vertices, and diagonals.

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I can define dimension and classify geometric objects by their dimensions.

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I can distinguish between polygons and non-polygons.

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I can name a 2-dimensional figure based on the number of sides.

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I can classify a polygon as regular or irregular.

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I can classify a polygon as concave or convex.

Dimensions

A dimension is a measurable distance. Length, width, and height (or depth) are dimensions.

Point

0 dimensions

Line

1 dimension (LENGTH)

Plane

2 dimensions (LENGTH and WIDTH)

Solid

3 dimensions (LENGTH, WIDTH, and HEIGHT)

2-Dimensional Polygons

A polygon is a closed figure with straight sides.

Which of the figures below are polygons?

1 2 3

4 5

Multiple Select

Choose all POLYGONS.

• 1

• 2

• 3

• 4

• 5

Polygons are named based on their number of
sides and vertices.

A side is a line segment
that forms a polygon.

A vertex is the point
where 2 sides meet.

Naming Polygons

3- sided polygon

triangle

4- sided polygon

quadrilateral

5- sided polygon

pentagon

6- sided polygon

hexagon

7- sided polygon

heptagon

8- sided polygon

octagon

We already know some of the polygon names!
Let’s fill out this table together.

9- sided polygon

nonagon

10- sided polygon

decagon

11- sided polygon

undecagon

12- sided polygon

dodecagon

n - sided polygon

n-gon

Any number can be substituted for n.

Naming Polygons continued...

A regular polygon is equilateral and equiangular.
That means that all sides and angles are congruent!

Remember!
Congruent parts need to be LABELED with hashmarks
(or have the same length/measure).
No assuming!

Regular Polygons

Irregular Polygons

Any polygon that is not regular is classified as irregular.
That means any side or angle is different from the others in the figure.

Regular vs. Irregular Polygons

Classify the following polygons as regular or irregular. Remember, congruent sides and angles must be labelled!

Multiple Select

Choose all REGULAR polygons.

• 1

• 2

• 3

• 4

Diagonals

A diagonal is a line segment that connects 2 vertices of a polygon that is NOT one of the sides

Diagonals help us classify a polygon as CONCAVE or CONVEX.

Convex Polygons

A polygon is convex if all of the diagonals are inside of the shape.

All of the angles of the polygon “poke out”

Concave Polygons

A polygon is concave if any diagonal goes outside of the shape.

At least one angle “caves in”

Convex vs. Concave Polygons

Classify the polygons shown as convex or concave.

Multiple Select

Choose all CONVEX polygons.

• 1

• 2

• 3

• 4

16

Exit Ticket

Keep your notes ready! We're going to answer a few problems as an exit ticket today.

These assignments we did in the last two weeks are going into THIS six weeks' gradebook:

1. Identifying Quadrilaterals Deltamath

2. Quadrilaterals Properties Quizizz

3. Questions #10-#14 on your "Right Triangles in Quadrilaterals" handout

4. Questions #4 & #5 on your "Name that Quadrilateral" handout (the 2nd page)

Multiple Choice

How many vertices are present on the shown figure?

• 4

• 5

• 6

• 2

Multiple Choice

Name the figure shown.

• Octagon

• Nonagon

• Decagon

• Septagon

Multiple Choice

Name the figure shown.

• Septagon

• Pentagon

• Octagon

• Hexagon

Multiple Select

Check all of the boxes that describe the figure shown.

• Quadrilateral

• Pentagon

• Concave

• Convex

Multiple Select

Check all of the boxes that describe the figure shown.

• Regular

• Irregular

• Pentagon

• Hexagon

• Concave

Multiple Select

Check all of the boxes that describe the figure shown.

• Concave

• Convex

• Dodecagon

• Decagon

• Irregular

Multiple Select

Check all of the boxes that describe that figure shown.

• Concave

• Convex

• Regular

• Irregular

• Hexagon

Multiple Select

Check all of the boxes that describe the figure shown. Remember, labels are important!

• Regular

• Pentagon

• Quadrilateral

• Concave

• Convex