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After making an ellipse in geometry app, how do I use measure to get it's area? I keep getting zero! I'm not getting this...!

Thanks! (The geometry app looks like fun).
(01-01-2016 09:07 PM)lrdheat Wrote: [ -> ]After making an ellipse in geometry app, how do I use measure to get it's area? I keep getting zero! I'm not getting this...!

Thanks! (The geometry app looks like fun).

It returns 0 for me as well.

The help for area() does not mention anything specifically about working for an ellipse. It does mention and returns non-zero results for circles however. I'm guessing that it's a limitation.
If you don't find information in HP documentation, you should have a look at Xcas: area currently supports circles and polygons. There is no special object for conics, they are stored as parametric curves in the CAS (Geometry uses CAS objects).
I can extend the area command to parametric curves (including ellipses but also function and polar plots) using Green-Riemann theorem, but for non closed curves you will be surprised by the sign. Indeed I must close the curve to apply Green-Riemann, it's natural to close it with vertical segments at the boundaries and the Ox axis, but then you will not follow the curve in the trigonometric way : I will in fact compute int(-y*dx) along the curve. Note also that the area will be computed in approx mode (because the plotting functions do numeric evaluation of the boundaries).
Parisse....

Have you ever added this functionality or have you not been present in the new update?
It's not implemented.
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