In GeoGebra beta it's now possible to have implicit curves like
a: sin(x) + sin(y) = 1
* the drawing algorithm is very simple and fails in some cases
* for independent curves, file sav + open does not work (fixed for next release)
* Point on curve
* Transforms: translate / dilate / rotate ...
* Commands: Tangent, Intersect, Curvature, CurvatureVector, ImplicitDerivative
In case you have some curves you think are important to work nicely, please list them in this topic.