# Parameter

Geometry Level pending

$\begin{cases} x=\dfrac{4\alpha }{1+\alpha ^2} \\ y=\dfrac{2-2\alpha ^2}{1+\alpha ^2} \end{cases}$

If reals $$x$$ and $$y$$ satisfy the system of equations above for real parameter $$\alpha$$. Find the range $$x^2-xy+y^2$$ lies within.

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