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