# Find a vector parametrization for: y^2+2x^2-2x=10

1. Nov 28, 2008

### kkranz_gatech

Find a vector parametrization for: y^2+2x^2-2x=10

My attempted solution is to say that x(t)=t and y(t)= +-sqrt(-2t^2+2t+10) but I don't think it's correct to have the +- and I might need to use polar coordinates instead. I'm just not sure of the function with the extra x in it.

2. Nov 28, 2008

### jeffreydk

Re: parametrize

Well this basically looks like an off-center ellipse as you can see from the x term, so you'll want to parametrize it using the trig identity $\cos^2x+\sin^2x=1$

What happens if you complete the square on the x term and make it as such?...

$$y=\sqrt{\frac{21}{2}}\sin{t}$$

$$x=\sqrt{\frac{21}{4}}\left(\cos{t}+\frac{1}{2}\right)$$