Consider a triangle \(ABC\) with
sides of the lengths \(4\, \mathrm{cm}\),
\(4\, \mathrm{cm}\) and
\(4\, \mathrm{cm}\). Identify the type
of the triangle \(ABC\).
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.
In the following list identify a line which is perpendicular to the line
\(q\).
\[
\begin{aligned}q\colon x& = 5 - t,&
\\y & = 3t,\ t\in \mathbb{R}
\\ \end{aligned}
\]
In the following list identify a line parallel to the line
\(q\).
\[
\begin{aligned}q\colon x& = t, &
\\y & = 1 + 5t,\ t\in \mathbb{R}
\\ \end{aligned}
\]