December 15th, 2012, 09:02 PM  #1 
Newbie Joined: Dec 2012 Posts: 1 Thanks: 0  need a help with 3d geometry
Find direction cosines of line perpendicular to lines with direction cosines proportional to (6,4,4) and (6,2,1).

December 16th, 2012, 06:13 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 20,281 Thanks: 1965 
Find a vector, such as (2, 3, 6), that is perpendicular to (6, 4, 4) and (6, 2, 1), then calculate ?(2˛ + 3˛ + 6˛) = 7. Dividing (2, 3, 6) by 7 gives (2/7, 3/7, 6/7).

December 16th, 2012, 03:00 PM  #3  
Global Moderator Joined: May 2007 Posts: 6,684 Thanks: 658  Re: need a help with 3d geometry Quote:
 

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