6.1 Polygons Textbook page 303. Definitions A polygon is a plane figure that is formed by three or...

6.1 Polygons

Textbook page 303

Definitions A polygon is a plane figure that is

formed by three or more segments called sides. (a closed, sided figure)

Each side intersects exactly two other sides at each of its endpoints. Each endpoint is a vertex of the polygon.

Two vertices that are endpoints of the same side are consecutive vertices.

A segment that joins two nonconsecutive vertices of a polygon is called a diagonal.

Verticesside

diagonal

Consecutive vertices

Is the figure a polygon? Why or why not?

Yes, the figure is closed and formed by straight sides

Is the figure a polygon? Why or why not?

No, one of the “sides” is not a segment – it is a curve

Is the figure a polygon? Why or why not?

No, two of the sides only intersect one other side – it is not a closed figure

Is the figure a polygon? Why or why not?

Yes, the figure is closed and formed by straight sides

Naming Polygons

Number of Sides Name of Polygon

3

4

5

6

7

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4

5

6

7

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5

6

7

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6

7

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8 Octagon

9

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8 Octagon

9 Nonagon

10

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8 Octagon

9 Nonagon

10 Decagon

12

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8 Octagon

9 Nonagon

10 Decagon

12 Dodecagon

n

Naming Polygons

Number of Sides Name of Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon or Hectagon

8 Octagon

9 Nonagon

10 Decagon

12 Dodecagon

n n-gon

Quadrilaterals

Quadrilaterals are made of two triangles. The sum of the angles in a triangle is 180o. 2 * 180 = 360

total 180o

total 180o

Quadrilateral Interior Angles Theorem

The sum of the interior angles of a quadrilateral is 360o.

m<1 + m<2 + m<3 + m<4 = 360o

4

1

3

2

Find the measure of <A

900

A

B

C

D

1100

600

1000

Find the measure of <A

650

AB

C

D

550

800

1600

Find the measure of <A

720

A

B

C

D

1080

720

1080

Homework

Assignment # 10 Textbook page 306 Problems 1-23, 30-42 You do not have to write the problems, but

you MUST show your work on 6,7, 15-20, and 37-42