The Tetrahedron Superyacht designed by Jonathan Schwinge is a regular tetrahedron with edges $20\,\text{m}$ long. The distance $r$ from one corner to the center of the base (shown in the picture below) is $11.5\,\text{m}.\,$
**What is the vertical height, $h$, of the tetrahedron?**
Round your answer to the nearest tenth of a meter.
The height is [[☃ input-number 1]] $\text{m}$.
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