SHAPES!

Introduction to some basic polygons

What do you know already?

How many shapes can you think of off the top of your head?

Where have you seen these shapes before?

What is a polygon?

2 dimensional

Closed

Made of straight lines

Which of these are polygons?

No

Yes

No

Triangle

Any three sided polygon

Types of Triangles:

Acute

Obtuse

Right

Scalene

Isosceles

Equilateral

Lets learn about the different kinds

Looking at side lengths

Scalene

All three sides of the triangle are different length

Isosceles

Two of the sides on the triangle are the same length

Equilateral

All three sides of the triangle are equal

Looking at the angles

Acute

ALL of the angles in the triangle is acute (less than 90°)

Obtuse

One of the angles in the triangle is an obtuse angle (greater than 90°)

Right

There is one right angle (90°) in the triangle

Parallelogram

Four sided polygon

Opposite sides are parallel

Rectangle

Polygon

4 sides

4 right angles (90°)

Parallelogram

Square

Special type of rectangle

Four EQAUL sides

Four 90° angles

Parallelogram

Rhombus

Another parallelogram

Opposite sides are parallel

Four EQUAL sides

Which is a rhombus?

Trapezoid

Only one pair of opposite sides are parallel

Four sides

Polygon, but NOT a parallelogram

Pentagon

Polygon

5 sided

Regular Pentagon has 5 equal sides

Which on is the regular pentagon and which is just a pentagon?

Polygon

6 sided

Regular Hexagon has 6 sides of equal length

Hexagon

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http://minglearound.files.wordpress.com/2010/12/nuts-bolts-washers.jpg

Octagon

Polygon

Eight sides

Regular octagon has 8 sides of equal length

Photo taken by Jillian Carey

Decagon

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Polygon

Ten sided figure

Regular decagon has ten equal sides

Which one of these is the regular decagon?