Que-two forces are acting on a body at angle of 60degree from each other and their magnitude are in the ratio of 3:5.if their resultant is 35N,then find out the magnitude of both the forces?
Answer-15N and 25N.
Sir but my answer is 525N and 875N.

There is no way that two forces of magnitudes 525n and 875N can act on an object and give a resultant force of only 35N. Can you see what that is? Hence you should be able to see right away that your answer must be incorrect.

To solve this you can use the law of cosines to find the magnitude of the resultant force C, in the same scale as A and B are given:

C^2 = A^2 + B^2 - 2ABcos(c)

where A = 3, B = 5, and angle c = 60 degrees. Once you have C, you'll ned to determine a scaling factor F such that

C x F = 35N

Once you have F you can multiply A by F and B by F to find their magnitudes.

One thing to be careful about - the angle c is either 60 degrees or 120 degrees, depending on which way the forces A and B are acting.