An Annulus is an object in the form of a ring (the area between two concentric circles). In order to calculate the annulus, it is necessary to input the dimensions of the inner and outer circles.
The number of decimal places is preset to be 2.
The user of the Annulus Calculator is capable of controlling the number of decimal places, he/she wants to calculate to.
The following algorithms are included into the Annulus Calculator
Area of the annulus (A0) = A1 - A2
A0 = π x (r12 - r22)
Diameter is the Radius x 2
Radius is the Diameter x 0.5
Circumference is π x Diameter
π is 3.141592654 (to 9 decimal places)