Length of common perpendicular - [Iran Second Round 1984]
Source:
December 30, 2010
Problem Statement
Let and be two lines with the equations
\frac{x-1}{2} = \frac{y-1}{3} = \frac{z-1}{4} \text{and} \frac{x+1}{2} = \frac{y+2}{4} = \frac{z-1}{3}.
Find the length of their common perpendicular.