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Published on December 11th, 2010 In category Education | Maths

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# Geometric formulas for Polygon

Some basic geometric formulas for regular polygon.  A regular polygon is one which has all the sides are equal

The area of a regular polygon is always = 1/2 (apotherm) x (perimeter)  : Refer to the illustration 2nd Image

If n = Numbers of side of the polygon , S  = Length of the side of the polygon, r = radius of the circumcircle, a = apotherm ) refer to the second image for illustration

1. Measure of the interior angle = [(n-2)/n] x 180 degrees

2. Sum of the interior angles = (n-2) x 180 degrees

3. The number of diagonals in a polygon = 1/2 [n x (n-3)]

4. The number of triangles (when you draw all the diagonals from one vertex) in a polygon = (n – 2)

5. Area of a regular polygon = (1/2) n sin(360°/n) s2

6. Interior Angle + Exterior Angles = 180o

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