kjf Posted March 6, 2010 Report Share Posted March 6, 2010 Hey guys, I'm not posting this up so I don't have to do it, I've done all of the calculations and everything and have a pretty reasonable idea on what I'm doing, but I'm just getting wrong answers. Triangle has 3 points (1, 0, 1), (6, 2, -7), (3, -2, 2). I named my points A, B and C respectively. I calculated AB, AC, BC and got AB = (-5, -2, 7)AC = (-2, 2, -1)CB = (-3, -4, 9) I then calculated magnitudes of each ||AB|| = sqrt 78||AC|| = 3||CB|| = sqrt 106 Dot Products were calculated aswell AB.AC = 15AC.CB = -7AB.CB = 86 Cos(theta) = AB.AC / ||AB||.||AC||Solved for theta and got 55.51 For AC and CB theta was 103.09 And finally AB and CB was 18.95 Which added up to approx 177 =/= 180. So I don't know what I'm doing wrong? I thought I had all of my working correct? If you guys could shed some light I'd greatly appreciate it, I dunno where I'm going wrong!? Cheers, Karl Quote Link to comment Share on other sites More sharing options...

sanctus Posted March 8, 2010 Report Share Posted March 8, 2010 Just looking at it quickly AB should be (-5,-2,8) and not 7 in z-entry. Tell me, if that makes you get [math]180^\circ[/math]... Quote Link to comment Share on other sites More sharing options...

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