Algebra Level 4

$\begin{cases}w^2 + x^2 + y^2 + z^ 2 = 20 \\ wxyz = 24 \end{cases}$

If $$w, x, y, z$$ are 4 real numbers such that the system of equations above is true, what is the maximum value of $$x^2 + y^2$$?

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