lesson 19 polygons
DESCRIPTION
Lesson 19 Polygons. Kalyani David. Objective. 1.Define polygon 2. Identify and describe polygons by the number of sides and angles 3. Explain the difference between regular and irregular polygons. What is a Polygon????. Any ideas? Write down what you think it is for . A polygon is…. - PowerPoint PPT PresentationTRANSCRIPT
Lesson 19 Polygons
Kalyani David
1. Define polygon2. Identify and describe polygons by the number of sides and angles3. Explain the difference between regular and irregular polygons
Objective
What is a Polygon????
Any ideas?Write down what you think it is for
a closed figure with three or more sides.
A polygon is…
A polygon is a closed figure
with 3 or more sides
(all straight lines, no curves).
Check your work
Polygon Not a polygonNot a polygon polygon
Polygon Not a polygon polygon Not a polygon
Check your work
Polygon polygon polygon Not a polygon
Polygon Not a polygonNot a polygon Polygon
Essential Question
Where do we see Polygons in our everyday Environment ?
Classifying Polygons
Triangle A triangle has three sides.
1
2
3
Quadrilateral A Quadrilateral has four sides.
1
2
3
4
Pentagon A pentagon has five sides.
1
2
3
4
5
Hexagon
A hexagon has six sides.
Heptagon
A heptagon has seven sides.
heptagon
Octagon
An octagon has eight sides.
8 sided Polygon = Octagon
Hint: “oct”opus – 8 legs
Number of Sides Name
3 Triangle
4 Quadrilateral
5 Pentagon
6 Hexagon
7 Heptagon
8 Octagon
9 Nonagon
10 Decagon
11 Hendecagon
12 Dodecagon
Classifying Polygons bynumber of Sides
Q: What do we call a polygon with more than 12 sides?
A : An ‘n’-gon where ‘n’ is the number of sidesEx: a 20 sided polygon is a 20-gon
Let’s Review:
The triangle is the smallest polygon. It only has three sides.
A pentagon has five sides. A hexagon has six sides. A heptagon has seven sides. An octagon has eight sides.
Match these.
Triangle eight sides
Heptagon three sides
Octagon seven sides
Match some more. Pentagon four sides
Hexagon five sides
Square six sides
A triangle is the smallest polygon because it has three sides. Can you have a two-sided polygon? Why or why not?
Two lines don’t close to make a shape. They make an angle.
2
1
Key Question:
Practice set and Written Practicefrom your Text
Page:123
Home Work