How do you find "C" in terms of A, B, and θ? vectors...?

http://session.masteringphysics.com/prob...





If you have that problem in the picture, how could you find "C" (not vector C) in terms of A, B, and θ?





The other angle, φ, isn't included in the final answer.


Angle "c" is not in the final answer either.





I'm struggling with this and would appreciate help.

How do you find "C" in terms of A, B, and θ? vectors...?
Well, the only "C" I see besides the angle is the vector. But I assume that you mean that you just want the magnitude of C. In which case, you have, by the law of cosines:





C²=A²+B²-2AB cos c





Of course, c=180°-θ, and cos (180°-θ) = -cos θ, and magnitudes are always positive, so:





C=√(A²+B²+2AB cos θ)





The angle of C is of course (the angle of A) + φ.





Edit: You're welcome.

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