Find the distance from (3,7,-5) to each of the following:

a)xy-plane

b)xz-plane

Can someone explain to me how this is done? there are parts c-f to all different planes and I want to see how it is done to a) and b) thanks.

2) Find an equation of a sphere if one of its diameters has endpoints (2,1,4) and (4,3,10).