Betrachte den Ellipsoid

${\displaystyle M={\left\{(x,y,z)\in \mathbb {R} ^{3}\mid \ {\frac {x^{2}}{a^{2}}}+{\frac {y^{2}}{b^{2}}}+{\frac {z^{2}}{c^{2}}}=1\right\}},}$

${\displaystyle {}a,b,c\in \mathbb {R} _{+}}$

${\displaystyle {}a=b}$

${\displaystyle {}a\rightarrow c}$