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posted by  C17 on 7/4/2009 1:22:54 AM  |  status: Live  |  Earned Karma: 35

angle between vectors

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If A  C = -7.5, A = 3i - 4j, and = 6.5, what is the angle between the two vectors when they are drawn starting from the same point?
a. 118 degrees
b. 107 degrees
c. 112 degrees
d. 103 degrees
e. 77 degrees
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posted by watt (MNK) on 7/4/2009 1:28:19 AM  |  status: Live
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Response Details:
Let angle be  θ   then
cos θ = A .C /[ magnitude of A * magnitude of C ]
Given  A .C = -7.5
    magnitude of C = 6.5
magnitude of A = √[ 3 ^ 2 + ( -4 ) ^ 2 ]
                        = 5
So, cos θ = 103.34 degrees
(SME)
posted by JamesD on 7/4/2009 1:28:41 AM  |  status: Live
Asker's Rating: Lifesaver   
Response Details:
I hope this helps! Best of luck with the rest of your coursework.
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