In this video we use GeoGebra 3D from to graph a cone with equation x^2 + y^2 - z^2 = 0 in rectangular and phi = pi/4 in spherical. Find out how to get the equation here: We use the surface command with parameters for theta and rho (I use t and r). After getting the graph to work we then create sliders for the upper bounds of the parameters and play around with it a bit. Playing around with this kind of thing on GeoGebra is the best way I've found to really learn what's going on.