Question 983479
{{{x^2/7^2+y^2=1}}}<-->{{{x^2/49+y^2=1}}}
If vertices and co-vertices are symmetrical with respect to the origin,
then the ellipse is centered at the origin.
The equation of an ellipse centered at the origin is
{{{x^2/a^2+y^2/b^2=1}}} .
When {{{x=0}}} , {{{y^2/b^2=1}}}--->{{{system(x=0,"with",y=-b,"or",y=b)}}} are the coordinates of vertices or co-vertices.
When {{{y=0}}} , {{{x^2/a^2=1}}}--->{{{system(y=0,"with",x=-a,"or",x=a)}}} are the coordinates of vertices or co-vertices.