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The resultant of vectors A and B has a magnitude of 20units. A has a magnitude of 8units and the angle between A and B is 40 degrees. calculate the magnitude of B?
 one year ago
 one year ago
The resultant of vectors A and B has a magnitude of 20units. A has a magnitude of 8units and the angle between A and B is 40 degrees. calculate the magnitude of B?
 one year ago
 one year ago

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rs32623Best ResponseYou've already chosen the best response.0
\[(8^{2}+B^{2}+2*8*B*Cos40)=20^{2}\] Can you proceed from here finding the value of B?
 one year ago

VincentLyon.FrBest ResponseYou've already chosen the best response.1
Use ruler and compass. You will get the value you need, then use geometry. Either resolve your vectors or work out magnitude directly using following link: http://en.wikipedia.org/wiki/Law_of_cosines
 one year ago

woleraymondBest ResponseYou've already chosen the best response.0
@rs32623 which formula are u using?
 one year ago

VincentLyon.FrBest ResponseYou've already chosen the best response.1
He is using the Law of cosines I mentioned above.
 one year ago

rs32623Best ResponseYou've already chosen the best response.0
i am using the formula for the resultant of two vectors A & B having magnitude A & B & angle between them if theta then the resultant is R=sqrt(A^2+B^2+2*A*B*Costheta)
 one year ago

woleraymondBest ResponseYou've already chosen the best response.0
i think the preferred solution is Resultant = \[sqrt{A^2 + B^2}\]
 one year ago

VincentLyon.FrBest ResponseYou've already chosen the best response.1
But this is true if and only if vectors A and B are at right angles.
 one year ago

woleraymondBest ResponseYou've already chosen the best response.0
if it is cosine rule then it should be R=sqrt(A^2+B^22*A*B*Costheta)....do you guys agree....@VincentLyon.Fr @rs32623
 one year ago

VincentLyon.FrBest ResponseYou've already chosen the best response.1
You should end up with B = 13.20
 one year ago
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