Question 722133
 

When the center of the ellipse is at the origin (0,0): 

{{{x^2/a^2+y^2/b^2=1}}}......for ellipses with horizontal major axes

{{{x^2/b^2+y^2/a^2=1}}}......for ellipses with vertical major axes


we will use this one in your case

{{{x^2/b^2+y^2/a^2=1}}}

{{{x^2/2500+y^2/8100=1}}}

{{{x^2/50^2+y^2/90^2=1}}}

semi-major axis: the longest radius of an ellipse

major axis: the longest diameter of an ellipse

so, in your case {{{semi-major_axis=90}}};so, major axis will be {{{180}}}