a resultant of two vectors makes 30 degree with one vector and 45 degree with the other. Find the two vectors if the resultant has the magnitude 15

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Let the resultant makes an angle of 300 with vector A such that :
β = 300
θ =750
and R = 15

As the resultant R makes an angle ​β with the direction of vector A.
Hence, tan ​β = B sin θA + B cos θ
tan 300B sin 750A + B cos 750
Solving, we get :
A = 1.41 B    .........(1)
and resultant is given by :
R = A 2 + B2 + 2 A B cos θ
Putting R = 15, A = 1.41 B and θ = 750 in above equation, we get :
B = 7.81 
Substituting value of B in eq. 1, we get :
A = 11.01
 

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