Question

If l₁, m₁ , n₁ and l₂, m₂, n₂ are the direction cosines of two mutually perpendicular lines, show that the direction cosines of the line perpendicular to both of these are m₁n₂ – m₂n₁, n₁l₂ – n₂l₁ l₁m₂ – l₂m₁

Answer 1

The given lines are respectively parallel to is a vector which is normal to both \(\vec{a_1}\) and \(\vec{a_2}\) and is of magnitude unity.