$ S_1 : (x-1)^2 +y^2+z^2=1 $
$S_2 : x^2 +y^2 +z^2 =1$
$S_3 : (x+1)^2 +y^2 +z^2 =1 $
Find the volume of the solid inside $S_2$ and outside $S_1$ and $S_3$, using triple integrals.
I have try to express the region enclosed by two spheres in spherical coordinates, but I am stuck... Could anyone help me please ?