\textbf{127-} Inside a regular quadrilateral solid with lateral edge $\sqrt{6}$ units and base edge $2\sqrt{6}$ units, the largest possible sphere is placed. What is the radius of this sphere in units?
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\hfill $1\ (1$ \hfill $\dfrac{4}{3}\ (2$ \hfill $\dfrac{3}{2}\ (3$ \hfill $2\ (4$
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