球极坐标系中(Spherical polar coordinates) x =rsine coso y=rsine sing z=r cos0 2=x2+y2+z2 Z c0s0= Vx2+y2+2 tanφ=y X 微体积元dx=dx dy dz=sinedr dedφ球极坐标系中(Spherical polar coordinates) z x y   r x = rsin cos, y = rsin sin, z = r cos r 2 = x2 + y2 + z2 2 2 2 x y z z cos + +  = x y tan  = 微体积元 d = dx dy dz = r2 sin dr d d