May 5th

•Math Notes
•May 5th, 2008
•Area Investigation
•what is the area of a triangle?
•1/2 bh.
•What if the triangle is an equilateral triangle then what is the formula
•Area Of an Equilateral Triangle
•The area of an equalateral is one fourth the square of the length of the side times the square root of 3.
•Area Investagation
•In a regular polygon, how many triangles can be formed with a vertex at the center and one side along the side of the polygon?
•Definitions
•Apothem- the distance from the center to any side of the polygon.
•Area Investigation
•calculate the area of a regular pentagon, in terms of the side length, s, and the apothem.
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•in terms of s and a what is the area of a heptagon?
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•in terms of s and a, what is th earea of an ngon?
•Tetrahedron
•A regular four sided 3-D shape.
•4 faces
•6 vertices
•Tetrahedron net
•Tetrahedron model
•Spin a tetrahedron
•Area Investigation
•Calculate the area of a regular pentagon, in terms of the side, s, and the apothem
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•The area of each triangle is 1/2 sa
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•There are 5 triangles, so the total area is 1/2 sa (5)
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•In terms of s and a what is the area of a heptagon?
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•In terms of s and a what is the area of a n-gon?
•Cube
•6 faces
•8 vertices
•12 edges
•Cube net
•Cube model
•Spin a cube
•Octahedron
•8 faces
•6 vertices
•12 edges
•Octahedron net
•Octahedron model
•Spin a octahedron