Polygons Download

Transcript
Exploring
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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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Can be “regular” – all sides and all angles are
equal to each other. Regular or irregular?
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Try to draw it in your notebook.
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Talk and Turn to discover whether this is
possible or not. Why or why not?
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TRIANGLES!
Two sides of equal
length
 Three acute angles
 Sum of angles = 180°
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Teacher:
When I say, isosceles,
you say 2 sides equal!
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Students:
Isosceles!
2 sides equal!
Isosceles!
2 sides equal!
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All sides equal length
Three acute angles
Sum of angles = 180°
Is a regular polygon
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Teacher:
When I say, equilateral,
you say all sides equal!
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Students:
Equilateral!
all sides equal!
Equilateral!
all sides equal!
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No sides are equal
No angles are equal
May have obtuse angle
Sum of angles = 180 °
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Teacher:
When I say, scalene, you
say NO sides equal!
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Students:
Scalene!
NO sides equal!
Scalene!
NO sides equal!
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By their angles!!
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Has 1 right angle!
90 degrees
The little square box in
the corner
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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.
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A triangle with one
obtuse angle (more
than 90 degrees)
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Talk and Turn: can you
make a triangle with
more than one obtuse
angle? Why or why
not?
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4 sides
4 angles
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QUAD = 4
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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°
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All sides equal
All angles equal and
are 90 ° each
 Sum of angles = 360 °
 Is a regular polygon
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Two sides are parallel
Has obtuse and acute
angles
 Sometimes has a right
angle
 Sum of angles = 360 °
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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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Opposite sides parallel
Opposite sides equal in
length
 Opposite angles equal
 Sum of angles = 360 °
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http://www.schooltube
.com/video/2020fa2f64
2304cf32e4/PolygonSong
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5 sides
Sum of angles = 540 °
Regular polygon
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6 sides
Sum of angles = 720 °
Can be regular polygon
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8 sides
Sum of angles = 1080 °
Can be regular polygon
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9 sided polygon
9 angles
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10 sides
Sum of angles = 1440°
Can be regular polygon