Geometric Formulas
Circle
area = 1/2 diameter x 1/2 circumference
area of sector = lenght of arc x 1/2 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 the semicircle = area of sector of equal radius minus area of triangle
circumference = diameter x 3.1416
radius x 6.283185
diameter = circumference x .3183
radius = circumference x . 0159155
Cylinder of Prism
Surface = (area 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 1/2 slant height + area of base
contents = 1/3 altitude x area of base
Rectangle
area = lenght x width
Sphere circumference = cube root of solidity x 3.8978
= square root of surface x 1.772454
Contents = diameter x .5236
content 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 diameter
volume = surface x 1/6 diameter
= diameter cubed x 05236
= radius cubed x 4.1888
= circumference cubed x 0.16887
Square Aea = length x width
Trapezium Area = divide trapezium into two triangles; add their areas
Trapezoid Area = altitude x 1/2 sum of parellel sides
Triangle Area = 1/2 altitude x base
Wedge contents = 1/2 altitude x area of base