[Math] Solve for y within a parametric equation

calculusfunctionsparametric

The ellipse

$$\frac{x^2}{2^2} + \frac{y^2}{3^2} = 1$$

can be drawn with parametric equations. Assume the curve is traced clockwise as the parameter increases.

If $x=2\cos t $

then $y =$ _____

I got $y=(9-(9x^2)/4)^{1/2}$ and then substitute $x$ for $2\cos t$ and got $y=(9-(9(2\cos t)^2)/4)^{1/2}$. What am I doing wrong?

Best Answer

you are doing nothing wrong. Just try to simplify your "final" expression you would find it is $3\sin(t)$ or $-3\sin(t)$.

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