Help on calc 3 problem would be incredibly appreciated...
ok... this problem is driving me nuts and I have till tomorrow (9/6/07) to figure it out.
It involves 3 dimensional vector math and dot products.
The task is to "find the magnitude of the projection of the load supporting cable OA (O being origin) onto the positive zaxis" as shown in a figure. The figure displays 3 vectors A, B, and C plus a 4th force vector going down the negative zaxis which is shown to have a force of 1000kg.
Points and their coordinates are as follows:
OA.) (10,5,20)
OB.) (5,5,20)
OC.) (5,5,20)
From there, I am a bit stuck. I know the formula of any projection of u onto v... but it doesnt seem to me it would work in this case, it just doesnt seem right. Trig appears to me to be involved but how to apply it sort of stumps me for some reason.
Any help (hints, strategies, etc.) would be helpful and greatly appreciated... thanks!
Joe
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Joeseph P. Smith University of Michigan  Informatics
