The excercise: Find a parameterization of the cutting curve between the surfaces. The parameterization must be such that y (t) = ksin (t) for a positive constant k, and so that the cutting curve is traversed counterclockwise as seen from above.
The equations: $$-3x^2+5z=1\qquad \text{og} \qquad 8x^2+7y^2=5$$
Until now I thought that I can start with working on the second equation. That is what I got: $$\frac85 x^2+\frac75 y^2=1$$
So this clearly is a equation for an ellipse. $X = a\cos(t)$ and $y = b\sin(t)$ when parameterized. So I thought that $a = b = \sqrt{5}$.
But it isn't the right answer. I don't quite understand what am I supposed to do with the numerators.