Perimeter formula for ellipse was shown to be in error by Kepler, more than 400 years ago; try Ramanujan 1, a simple formula only little more than a 100 years old.
I think all the questions asked are important to the app, and it must be introduce in it
Sooper... App.. It is very use full App for us
Duke Its gud
Angles??? What about formulas for calculating angles?!