I am having trouble trying to figure out how to project a 3D angle onto two datum planes so that I can measure the 3D angle relative to my WCS. I have a surface that is placed at some compound angle. I am trying to project a vector normal to this surface on the "top"and "side" planes so that I can more easily measure the surface's compound angle. I see that the angle analysis tool should allow me to project my angle on the WCS XY plane, but I can't seem to get this to work. I pick my surface, but then it prompts me to pick a second reference. Shouldn't this second reference be the WCS XY plane like the tool suggests?