Two systems of rectangular axes have the same origin. If a plane cuts them at a distance  of a, b, c and a', b', c' respectively from the origin then $\frac{1}{{\mathrm{a}}^2}+\frac{1}{{\mathrm{b}}^2}+\frac{1}{{\mathrm{c}}^2}=\mathrm{K}\left(\frac{1}{{\mathrm{a}}^{\mathrm{\prime }2}}+\frac{1}{{\mathrm{b}}^{\mathrm{\prime }2}}+\frac{1}{{\mathrm{c}}^{\mathrm{\prime }2}}\right)$ where k =