As per Astronuc request, i will post this here so it can benifiet other people who may have similar questions. I have this Linear Algebra assignment to do and i was completely stomped on how to go about to answer this question. I asked Astronuc for help to clarify a bit what was asked to understand it more. 1. The problem statement, all variables and given/known data the question goes as follows, If a>0,b>0,c>0. find the point on the plane x/a+y/b+z/c=1 which is closest to the origin (0,0,0) i need to justify this using vectorial reasoning. 2. The attempt at a solution after sending a PM to Astronuc i came across a site which described me something related to my problem. unfortunately i cannot find it anymore i printed out what was written there. Astronuc replied to me with the following suggestions.