As I understand to plot a surface in spherical coordinates we most establish the function relationship of  the radius in terms of theta and phi.  Then using plot3d and specifying coords=spherical gives you surface.  How does one do this for a cone:

A link to a Maple10 worksheet is attached below.  The worksheet has the command lines but has not been executed so it size came under the limit for uploading.  The worksheet is an effort to animate the radius vector to a spacecurve complete with the tangent vector and associated normal and binormal vectors.  Early in the worksheet we suceed in animating the radius vector and the spacecurve.  This success was achieved with some pain.  For instance errors with the plot structures na ddisplay command would not work unless the whole sheet was executed - if, after this,

In an effort to draw the unit normal of a vector, n, to a curve defined by a radius curve, r, the following command is inputted to Maple but recieves the error also noted below.

arrow([0,0,0],eval(convert(n,list),t=0*Pi),shape=cylindrical_arrow,color=black);

Error, (in simpl/abs) abs is not differentiable at 0

 However a plot of the components of the unit vector shows that it is well behaved at 0, i.e. it has values of <-1,0,0>