# Is it geometry II?

Geometry Level 5

Let $$x$$, $$y$$ and $$z$$ be positive real numbers such that: $\begin{cases} x^2+xy+y^2=25 \\ y^2+yz+z^2=144 \\ z^2+zx+x^2=169 \end{cases}$ Compute the value of $${ \left( xy+yz+zx \right) }^2$$

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