Petersen–Morley theorem
In geometry, the Petersen–Morley theorem states that, if
are three general skew lines in space, if
are the lines of shortest distance
respectively for the pairs, and,
and if, and
are the lines of shortest distance respectively
for the pairs, and, then there
is a single line meeting at right angles all of
and
The theorem is named after Johannes Hjelmslev and Frank Morley.