Polygons

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Polygons

• Exploring

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What is a polygon?

• Polygons are many-sided figures, with sides that
  are line segments.
• Polygons are named according to the number of
  sides and angles they have.

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Polygon or NOT?
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Polygon or NOT?
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Regular or Irregular?

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

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Can you make a 2-sided polygon?

• Try to draw it in your notebook.
• Talk and Turn to discover whether this is
  possible or not. Why or why not?

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What are 3-sided polygons called?

• TRIANGLES!

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Isosceles Triangles

• Two sides of equal length
• Three acute angles
• Sum of angles 180

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Isosceles Chant!

• Teacher
• When I say, isosceles, you say 2 sides equal!
• Isosceles!
• Isosceles!

• Students
• 2 sides equal!
• 2 sides equal!

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Equilateral Triangles

• All sides equal length
• Three acute angles
• Sum of angles 180
• Is a regular polygon

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Equilateral Chant!

• Teacher
• When I say, equilateral, you say all sides equal!
• Equilateral!
• Equilateral!

• Students
• all sides equal!
• all sides equal!

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Scalene Triangles

• No sides are equal
• No angles are equal
• May have obtuse angle
• Sum of angles 180

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Scalene Chant!

• Teacher
• When I say, scalene, you say NO sides equal!
• Scalene!
• Scalene!

• Students
• NO sides equal!
• NO sides equal!

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Another way to classify triangles!

• By their angles!!

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Right Triangle

• Has 1 right angle!
• 90 degrees
• The little square box in the corner

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Talk and Turn

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

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Acute Triangle

• 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.

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Obtuse Triangle

• 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?

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What do you call a 4-sided polygon?

• 4 sides
• 4 angles
• QUAD 4

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Quadrilateral Classification

• There are many types of SPECIAL quadrilaterals

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Rectangles

• Opposite sides are parallel
• Opposite side are equal in length
• Each angle equals 90
• Sum of angles 360

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Squares

• All sides equal
• All angles equal and are 90 each
• Sum of angles 360
• Is a regular polygon

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Trapezoids

• Two sides are parallel
• Has obtuse and acute angles
• Sometimes has a right angle
• Sum of angles 360

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Rhombuses (rhombi)

• All four sides of equal length
• Opposite angles are equal 2 acute angles, 2
  obtuse angles
• Sum of angles 360
• Regular polygon

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Parallelograms

• Opposite sides parallel
• Opposite sides equal in length
• Opposite angles equal
• Sum of angles 360

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Just a Boring Square

• http//www.schooltube.com/video/2020fa2f642304cf32
  e4/Polygon-Song

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Pentagons

• 5 sides
• Sum of angles 540
• Regular polygon

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Hexagons

• 6 sides
• Sum of angles 720
• Can be regular polygon

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Octagons

• 8 sides
• Sum of angles 1080
• Can be regular polygon

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Nonagon

• 9 sided polygon
• 9 angles

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Decagons

• 10 sides
• Sum of angles 1440
• Can be regular polygon