i always had an intuition that formulas of coordinate formulas can be derived by use of cones (such as general equations of parabola etc.) Can anybody please help me. And another Question : is there any relation between semivertical angle of a cone and the angle between coordinate axes.
some more observations of mine - a cone can be cut into a plane extending to infinity in all directions. also shifting the vertex of cone like shifting of origin can help explain presence of imaginary lines passing through any point on the coordinate plane