When solving for the c squared while trying to find the foci of an Ellipses?

in the equation c^2 = a^2 - b^2, if c^2 turns out to be a negative number do u continue to working the problem with imaginary numbers or undefined. It also asks you to graph and I don't think we have learned to graph imaginary numbers if that is possible

When solving for the c squared while trying to find the foci of an Ellipses?
You suppose that a is the greater axis(half axis) so c^2 never can be negativ
Reply:"a" is the semi-major axis of the ellipse and "b" is the semi-minor axis. Therefore





a ≥ b





Therefore





c² = a² - b² ≥ 0


c ≥ 0





Consequently "c" can never be negative.