# A Challenging Problem of Tetrahedron by H.C.R

Geometry Level 5

The diagram above shows a tetrahedron with vertices $$A,B,C,D$$. If the angles between the lateral edges $$AC$$ & $$AD$$, $$AB$$ & $$AD$$ and $$AB$$ & $$AC$$ meeting at the vertex $$A$$ are $$\alpha =40^\circ, \beta=70^\circ , \gamma=85^\circ$$ respectively, then calculate the correct value (up to three decimal points) of the solid angle (in Ste-radian) subtended by triangular face $$BCD$$ at the vertex $$A$$.

×