Finding formulas for Polygons

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Finding formulas for Polygons

• With Classification
• Eric Bitter

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A Polygon is
plane figure a set of points in the same plane
enclosing a region.

• A closed plane figure.
• With at least three sides.
• The sides meet only at their endpoints.

plane figure
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Triangles Are Polygons With Three Sides
Classifying Triangles by angle measure
Acute
All angles are less than 90
all acute angles
Right
One angle is exactly 90
90 angle
Obtuse
One angle is greater than 90
obtuse angle
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A triangle is a polygon with three sides

• Classified by side lengths
• Equilateral Triangle three congruent sides
• Isosceles Triangleat least two congruent sides
• Scalene Triangleno congruent sides

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Classifying Quadrilaterals (4-sided enclosed
figures)
Quadrilateral four sides
Trapezoid exactly 1 pair of parallel sides
Parallelogram both pairs of opposite sides
parallel
Within this family are two special
quadrilaterals The Trapezoid with one set of
parallel sides. The Parallelogram with two sets
of parallel sides.
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Classifying Quadrilaterals (4-sided enclosed
figures)
Within this family are two special
Parallelograms The Rhombus with four congruent
sides. The Rectangle with four 90 angles..
Quadrilateral four sides
Parallelogram both pairs of opposite sides
parallel
Rhombus four congruent sides
Rectangle four 90 angles
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Classifying Quadrilaterals (4-sided enclosed
figures)
Within this family is a special Rectangle/Rhombus
called a Square.
Rhombus four congruent sides
Square four 90 angles and four congruent sides
Rectangle four 90 angles
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Classifying Quadrilaterals (4-sided enclosed
figures)
The Quadrilateral family at a glance.
Quadrilateral four sides
Trapezoid exactly 1 pair of parallel sides
Parallelogram both pairs of opposite sides
parallel
Rhombus four congruent sides
Square four 90 angles and four congruent sides
Rectangle four 90 angles
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Algebraic Thinking with Regular Polygons(all
sides and all angles are congruent)

• Use algebra to write a formula for the perimeter
  of a regular polygon--

Square
Pentagon
Hexagon
Triangle
4-sided
5-sided
6-sided
3-sided