In the cube \(ABCDEFGH\) find the
angle between the lines \(S_{BE}S_{AH}\)
and \(HC\), where
\(S_{BE}\) and
\(S_{AH}\) are centers of
the segments \(BE\)
and \(AH\),
respectively.
In the cube \(ABCDEFGH\) find the
angle between the lines \(S_{HD}S_{FC}\)
and \(AB\), where
the points \(S_{HD}\)
and \(S_{FC}\) are
centers of \(HD\)
and \(FC\),
respectively.
The side of a regular hexagonal prism
\(ABCDEFA'B'C'D'E'F'\) is
\(a = 3\, \mathrm{cm}\) and the height
\(v = 8\, \mathrm{cm}\). Find the length
of the diagonal \(AD'\).
Identify a valid relation involving the angle
\(\alpha \)
defined as an angle between a solid diagonal and a face diagonal through the same
vertex in a cube.