You do have many math questions.
If you expect us to do your homework for you, you should post under an appropriate category. I started this morning answering this question with time-consuming diagrams but did not finish and did not post the answer. During the day I tried to locate your question but for the longest time could not until I launched an all Google search over the Internet and found it. Why should anybody go through all this grief to help you?
Well I just did not want my previous work to go to waste.
I hope it helps somebody.
OACB is a parallelogram. R is the resultant.
Use the cosine law in the triangle OAC
R^2=(F_1)^2+(F_2)^2 -2(F_1)(F_2) cos (angle OAC)
Replace the variables by their known values and reduce your equation to
cos (angle OAC) =-53/112. Solve for
angle OAC in degrees
angle OAC =arccos(-53/112). The angle between the two vectors is the
supplementary of angle OAC
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