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Chapter 15 Lesson 3Chapter 15 Lesson 3
QuadrilateralsQuadrilaterals
and Other Polygonsand Other Polygons
A A polygonpolygon
is a flat, closed figure that is made up of is a flat, closed figure that is made up of three or more straight line segments called three or more straight line segments called sides sides . .
FLATFLAT CLOSEDCLOSED 3 or MORE STRAIGHT SIDES3 or MORE STRAIGHT SIDES
A A vertexvertex
is the point where two sides of a polygon is the point where two sides of a polygon meet.meet.
Show me a Show me a vertexvertex! ! Hint- Remember the Very, Very Tickly spot?Hint- Remember the Very, Very Tickly spot?
A polygon can be named by the number of sides it has.
These Are Polygons:
TriangleTriangle“tri” means 3“tri” means 3
3 sides3 sides 3 angles3 angles
QuadrilateralQuadrilateral“quad” means 4“quad” means 4
4 sides4 sides 4 angles4 angles
PentagonPentagon“pent” means 5“pent” means 5
5 sides5 sides 5 angles5 angles
HexagonHexagon“hex” means 6“hex” means 6
6 sides6 sides 6 angles6 angles
OctagonOctagon“octo” means 8“octo” means 8
8 sides8 sides 8 angles8 angles
These Are These Are Not Not PolygonsPolygons::Can you tell me why?Can you tell me why?
Some QuadrilateralsHave Special Names
A A rectanglerectangle
has opposite sides that are parallel has opposite sides that are parallel four right angles.four right angles.
A A squaresquare
has four sides of the same length has four sides of the same length four right anglesfour right angles
A A trapezoidtrapezoid
has only one pair of parallel sides.has only one pair of parallel sides.
What does that sound like? TRAP reminds me of a trap that What does that sound like? TRAP reminds me of a trap that gets skinnier and skinnier as you go in! Then, POOF! You gets skinnier and skinnier as you go in! Then, POOF! You are trapped!are trapped!
A A parallelogramparallelogram
has opposite sides that are parallel.has opposite sides that are parallel.
A A rhombusrhombus
has opposite sides parallel has opposite sides parallel four sides of the same lengthfour sides of the same length..
Quadrilateral GameQuadrilateral Game
Each student needs to get one Each student needs to get one dice, a pencil, and a piece of dice, a pencil, and a piece of
paper. paper.
You and the person across from You and the person across from you are partners. If we have a you are partners. If we have a
group of 3, that is fine too!group of 3, that is fine too!
Take turns rolling the diceTake turns rolling the diceand name the figure that has that and name the figure that has that
many sides.many sides.
((1 and 2 rolls do NOT make quadrilaterals. Skip to 1 and 2 rolls do NOT make quadrilaterals. Skip to the next player.)the next player.)
See how many you can quietly See how many you can quietly get right in the next 2 minutes.get right in the next 2 minutes.