1. The problem statement, all variables and given/known data http://www.flickr.com/photos/coolamasta/4563408911/ [Broken] 2. Relevant equations v . w = ||v|| ||w|| cos q 3. The attempt at a solution i calculate until i got the lambda value is 8/3. then i compare it with 21 and the answer is wrong. i dunno what to do. please help. tq.