Cartesian equation of an object in space

See Section 26.12.7 for Cartesian equations of 2D objects.

The equation command finds equations for geometric objects.

equation takes G, a geometric object.
equation(G) returns Cartesian equations in x, y and z which specify the object G.
The variables x, y and z must be unassigned. If they have assignments, they can be unassigned with purge(x,y,z).

equation(line(point(0,1,0),point(1,2,3)))

x−y+1=0,3 x+3 y−2 z−3=0

equation(sphere(point(0,1,0),2))

x²+y²−2 y+z²−3=0