Hello, and thanks for this important forum.
I have two problems in the use of the Plot3D instruction.
The first problem is that I desire to emphasize the region of the space (in a Plot3D) given by the intersection bewteen two surfaces (each one function of x and y). It is necessary that the two surface and the region in the Plot3D are coloured with three different color.
The another problem is the follow.
One of the two surfaces of the previous problem is a plane; I have for this the necessity to draw in the 3D plot, the ortoghonal rect to this plane.
Thank you very much