8.4. In the tetrahedron $E F G H$, it is known that $E F=G H=7, E G=F H=10, E H=F G=11$. Points $K, L, M, N$ are the centers of the circles inscribed in triangles $E F G, E F H$, $E G H$ and $F G H$. Find the volume of the tetrahedron $K L M N$. Round the answer to the nearest hundredth if necessary.
Answer: 2.09 (exact value: $\frac{\sqrt{215}}{7}$ ).