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woleraymond
 3 years 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?
woleraymond
 3 years 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?

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rs32623
 3 years ago
Best 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?

VincentLyon.Fr
 3 years ago
Best ResponseYou've already chosen the best response.1Use 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

woleraymond
 3 years ago
Best ResponseYou've already chosen the best response.0@rs32623 which formula are u using?

VincentLyon.Fr
 3 years ago
Best ResponseYou've already chosen the best response.1He is using the Law of cosines I mentioned above.

rs32623
 3 years ago
Best ResponseYou've already chosen the best response.0i 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)

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

VincentLyon.Fr
 3 years ago
Best ResponseYou've already chosen the best response.1But this is true if and only if vectors A and B are at right angles.

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

VincentLyon.Fr
 3 years ago
Best ResponseYou've already chosen the best response.1You should end up with B = 13.20
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