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.