Message text written by "John Carmichael" >At risk again of exposing my limited math skills, I was wondering if it would be possible to get an approximation of the area of an elipse by the following method: Average the length of the major an minor axises and then apply the formula for the area of a circle to this value, treating it as the diameter of a circle. example: If the major axis equals 4 cm. and the minor axis equals 2 cm. then their average length is 3 cm. The area of a circle is pi times the diameter. So , 3 times pi = 9.42 square cms.
(p.s. I'm thinking that you could use the formula for the circumference of a circle in the same way to get the circumference of an elipse. ) Thanks< There's no problem finding the area of an ellipse - there is an exact formula for that. The sort of approximation you consider for the circumference is behind Ramanujan's approximation too. Only he uses a more elaborate method than a simple mean and as a result his formula is exact for the case where the ellipse is virtually a circle and only a few percent out when it is nearly a straight line... Patrick
