If any tangent to the ellipse $\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1$ cuts off intercepts of length h and k on the axes, then $\frac{{{a}^{2}}}{{{h}^{2}}}+\frac{{{b}^{2}}}{{{k}^{2}}}=$