plot the ellipses x^2/a^2+y^2/16=1 and x^2/16+y^2/a^2=1.

Question

Create a slider, plot the ellipses x^2/a^2+y^2/16=1 and x^2/16+y^2/a^2=1. What is
the difference between the two ellipses? How does change in a affects the ellipse?

Answer 1

If asked to plot these ellipses, you should know what the value of a is.  (If a=4, these ellipses coincide.

Depending on how "a" compares to 4, the major axis direction changes (direction of elongation of ellipse); when a< 4, the first ellipse has vertical major axis and the 2nd ellipse has horizontal major axis.  Both ellipses have their center at the origin.