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Basic Postulates & Theorems of Geometry


Classifications | Formulas

Polygons Classifications
Polygons are classified according to their sides
 
No. of Sides Kind of Polygon No. of Sides Kind of Polygon
3 Triangle 7 Heptagon
4 Quadrilateral 8 Octagon
5 Pentagon 9 Nonagon
6 Hexagon 10 Decagon
 
Regular Polygon Formulas
 
Pentagon
Hexagon
Octagon
Perimeter
P=5R sqrt(10-2 sqrt[5])/2 P=6R P=8R sqrt(2-sqrt[2])
Area
K=5a sqrt(4R2-a2)/4 K=3a sqrt(4R2-a2)/2 K=2a sqrt(4R2-a2)

Where:
Perimeter: P
Area: K
Radius of circumscribed circle: R
Sides, all equal length: a