Hey there. This one has me kind of stumped. Maybe I was just a bit burnt out today, as I'd already done a few hours of work before I tried to tackle this problem. Spent a good long while on it without much luck. I'm tossing it out here in the hopes that someone might be able to give me a helpful hint or nudge in the right direction.
A flashlight located at the origin (0, 0, 0) shines a beam of light towards a flat mirror. The beam reflects off of the mirror at (8, 4, 1) and then passes through (10, 8, 5). What is the equation of the plane that contains the mirror?
Point-Line Distance--3-Dimensional -- from Wolfram MathWorld
hope this helps