Exploring

Polygons are many-sided figures, with sides that are line segments.

Polygons are named according to the number of sides and angles they have.

Can be “regular” – all sides and all angles are equal to each other. Regular or irregular?

Try to draw it in your notebook.

Talk and Turn to discover whether this is possible or not. Why or why not?

TRIANGLES!

Two sides of equal length

Three acute angles Sum of angles =

180°

Teacher: When I say,

isosceles, you say 2 sides equal!

Isosceles!

Isosceles!

Students:

2 sides equal!

2 sides equal!

All sides equal length

Three acute angles Sum of angles =

180° Is a regular

polygon

Teacher: When I say,

equilateral, you say all sides equal!

Equilateral!

Equilateral!

Students:

all sides equal!

all sides equal!

No sides are equal No angles are

equal May have obtuse

angle Sum of angles =

180 °

Teacher: When I say, scalene,

you say NO sides equal!

Scalene!

Scalene!

Students:

NO sides equal!

NO sides equal!

By their angles!!

Has 1 right angle! 90 degrees The little square

box in the corner

Can you make a triangle with 2 right angles? Why or why not?

Triangle with all angles LESS than 90 degrees.

The curve shows that it is an acute angle.

ALL triangles have some acute angles.

An acute triangle is special, because it has ALL acute angles.

A triangle with one obtuse angle (more than 90 degrees)

Talk and Turn: can you make a triangle with more than one obtuse angle? Why or why not?

4 sides 4 angles

QUAD = 4

There are many types of SPECIAL quadrilaterals

Opposite sides are parallel

Opposite side are equal in length

Each angle equals 90°

Sum of angles = 360°

All sides equal All angles equal

and are 90 ° each Sum of angles =

360 ° Is a regular

polygon

Two sides are parallel

Has obtuse and acute angles

Sometimes has a right angle

Sum of angles = 360 °

All four sides of equal length

Opposite angles are equal – 2 acute angles, 2 obtuse angles

Sum of angles = 360 °

Regular polygon

Opposite sides parallel

Opposite sides equal in length

Opposite angles equal

Sum of angles = 360 °

http://www.schooltube.com/video/2020fa2f642304cf32e4/Polygon-Song

5 sides Sum of angles =

540 ° Regular polygon

6 sides Sum of angles =

720 ° Can be regular

polygon

8 sides Sum of angles =

1080 ° Can be regular

polygon

9 sided polygon 9 angles

10 sides Sum of angles =

1440° Can be regular

polygon