Polygons and Quadrilaterals

Polygons

•The word polygon means “many angles”

What is a Polygon?

•A closed figure•Made up of three or more straight lines•The sides do not cross each other

These are polygons

These are Not Polygons because. . .

Only two lines

Lines are not straight

Not Closed

Lines Cross

Pentagon• A pentagon has five sides.

1

2

3

4

5

Hexagon and Heptagon

• A hexagon has six sides. (Hexagon and six both have an “x”.)

• A heptagon has seven sides.

hexagon heptagon

Octagon

• An octagon has eight sides. Count the sides.

Nonagon9 sides

DecagonTen Sides

Let’s Review:

• A pentagon has five sides.

• A hexagon has six sides.

• A heptagon has seven sides.

• An octagon has eight sides.

• A nonagon has nine sides

• A decagon has ten sides

Quadrilaterals

parallelogramrectangle

rhombus square

trapezoid

Definition• Quadrilateral – a polygon with

4 angles and 4 straight sides.

“Quad” means four. Why would all of these shapes be called “quadrilaterals”?

Each shape has four sides.

square

parallelogram

rhombus

rectangle

Quadrilaterals

trapezoid

The angles add up to 360º

65º

115º65º

115º

65º65º

115º115º+360º

Square• A square has four sides that are each the

same length.

• It also has four right angles (perfect corners).

1

2 3

4

Rhombus• A rhombus has four sides that are each

the same length.

• But it has two acute and two obtuse angles.

acute

acuteobtuse

obtuse

Square and Rhombus

• A square and a rhombus both have four sides that are the same length. So, how are they different?

Square and Rhombus

• A rhombus can be thought of as a slanted square.

• If we push on the left-hand side of this square, it might end up looking like…

a rhombus.

The only difference between a square and a rhombus is

their angles.

Trapezoid• A trapezoid has four sides.

• Two sides are parallel.

• The opposing two sides are not parallel.

Those are parallel.

Those are not parallel.

Rectangle•A rectangle has four sides – two long sides and two short sides.

•Two sides are parallel.

•The opposing two sides are also parallel.

•It also has four right angles.

Parallelogram•A parallelogram has four sides – two long sides and two short sides.

•Two sides are parallel.

•The opposing two sides are also parallel.

•But, it has two acute and two obtuse angles.

Rectangle and Parallelogram

• A parallelogram can be thought of as a slanted rectangle.

• If we push on the left-hand side of this rectangle, it might end up looking like…

a parallelogram.

The only difference between a rectangle and a parallelogram

is their angles.

QuadrilateralsSHAPE SIDES ANGLES PARALLEL

LINES

Square 4 same length

4 right angles 2 sets

Rhombus 4 same length

2 acute2 obtuse

2 sets

Trapezoid different lengths

different angles 1 set

Rectangle 2 long, 2 short

4 right angles 2 sets

Parallelogram 2 long, 2 short

2 acute 2 obtuse

2 sets

Now that you are done, go to the websites to play the games

• http://www.mathplayground.com/matching_shapes.html

• http://www.aaamath.com/geo318-polygons-numbers.html