[tex]\frac{g_{s}\cdot R^{2}_{s}}{(R_{s}+h)^{2}} = g_{z} \ \ /\cdot(R_{s}+h)^{2}\\\\\\g_{z} \cdot(R_{s}+h)^{2}=g_{s}\cdot R_{s}^{2} \ \ /:g_{z}\\\\\\(R_{s}+h)^{2} = \frac{g_{s}}{g_{z}}\cdot R_{s}^{2} \ \ |\sqrt{}\\\\\\R_{s}+h = R_{s}\sqrt{\frac{g_{s}}{g_{z}}}\\\\\\h = R_{s}\sqrt{\frac{g_{s}}{g_{z}}}-R_{s}\\\\\\\boxed{h = R_{s}\left(\sqrt{\frac{g_{s}}{g_{z}}}-1\right)}[/tex]
