GEOMETRIC FORMULAS

GEOMETRIC FORMULAS
Circle
Area	=		½ diameter x ½ circumference
Area of sector	=		Length of arc x ½ radius
Area of segment which is greater than semicircle	=		Area of sector of equal radius plus area of triangle
Area of segment which is less than semicircle	=		Area of sector of equal radius minus area of triangle
Circumference	=		Diameter x 3.1416 radius x 6.283185
Diameter	=		Circumference x .31 83
Radius	=		Circumference x .0159155
Cylinder or Prism Surface	=		( area of both ends) + ( length x circumference)
Ellipse Area	=		Product of the two diameters x .7854
Parabola Area	=		2/3 altitude x base
Parallelogram Area	=		altitude x base
Polygon ( Regular) Area	=		Sum of sides x perpendicular from center to one of sides / 2

Pyramid or Cone

Surface

=

Circumference of base x ½ slant height + area of base

Rectangle Area	=	Length x width
Sphere
Circumference	=	Cube root of solidity x 3.8978 square root of surface x 1.772454
Contents	=	Diameter x .5236
Contents of Segment	=	(height squared + three times the square of radius of base) x ( height x .5236)
Diameter	=	Square root of surface x .56419 cube root of solidity x 1.2407
Surface	=	Circumference x diamter
Volume	=	Surface x 1/ 6 diameter diameter cubed x .5236 radius cubed x 4.1888 circumference cubed x .016887
Square Area	=	Length x width
Trapezium Area	=	Divide trapezium into two triangles; add their areas
Trapezoid Area	=	Altitude x ½ sum of parallel sides

Triangle Area	=	½ altitude x base
Wedge Contents	=	½ altitude x area of base