Deduction of the area of a spherical spindle

It is very easy!! We apply the process by which there is calculated the value of a directly proportional magnitude to other one, ie, we use a rule of three direct.

We know that the area of a sphere is: {4.Pi.R^2}.So, we have the following:

{4.Pi.R^2} right360º
                                         ⇒    tabular{11}{11}{{x={4.Pi.R^2.nº}/{360º}}};-)
x          right



where nº is the number of degrees that the spindle has.