Question 5
Let $P$ be a plane and let $d,d'$ be two skew lines meeting $P$ at $A,A'$, respectively. Let $d''$ range over lines parallel to $P$ and meeting $d,d'$ at $M,M'$, respectively.
(a) Determine the position of $d''$ for which $MM'$ is shortest.
(b) Given a line $d''_0$, determine among the lines $d''$ the line $d''_1$ perpendicular to $d''_0$.
(a) Determine the position of $d''$ for which $MM'$ is shortest.
(b) Given a line $d''_0$, determine among the lines $d''$ the line $d''_1$ perpendicular to $d''_0$.