<image>As shown in the figure, it is known that the hyperbola $$y=\dfrac{k}{{x}}(k < 0)$$ passes through the midpoint $$D$$ of the hypotenuse $$OA$$ of the right-angled triangle $$Rt\triangle OAB$$, and intersects the leg $$AB$$ at point $$C.$$ If the area of $$\triangle AOC$$ is $$6$$, then the value of $$k$$ is _____
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