Give the equation for the ellipse with foci at (0, +/-2) and semi-major axis 3.
I find that:
a = 3
b = sqrt(5)
c = +/- 2
Thus by the standard equation of the ellipse:
x^2/a^2 + y^2/b^2 = 1
x^2/9 + y^2/5 = 1
However, the correct answer is supposed to be:
x^2/5 + y^2/9 = 1
What is wrong with my approach?