Editing Sphere (section)

===Intersection of a sphere with a more general surface===
[[File:Is-spherecyl5-s.svg|thumb|upright=0.8|General intersection sphere-cylinder]]

If a sphere is intersected by another surface, there may be more complicated spherical curves.
;Example: sphere–cylinder
{{Main|Sphere–cylinder intersection}}
The intersection of the sphere with equation <math>\; x^2+y^2+z^2=r^2\;</math> and the cylinder with equation <math> \;(y-y_0)^2+z^2=a^2, \; y_0\ne 0\; </math> is not just one or two circles. It is the solution of the non-linear system of equations
:<math>x^2+y^2+z^2-r^2=0</math>
:<math>(y-y_0)^2+z^2-a^2=0\ .</math>
(see [[implicit curve]] and the diagram)