In or ?
Anyway, if you derivate you'll get , so the tangent line in has a slope equal to , therefore the normal line to the curve in that point has a slope . Let then your vector is .
It's actually unusual for a curve in two dimensions as parametric equations since it is simpler to write it as a single xy equation. If that was a problem and you knew how to find a normal vector for a parameterized curve, let x itself be the parameter: x= t, y= .