Oh, ok, so if you must use it then magnitude and angle are easy to find but the real problem is the direction of net force.@The Vinh
i am aware that using Coordinates system axis is easier, however the lesson that i am doing requires that i learn their method, and it involves the cosine law etc..
they don't provide any other ways to solve and they are expecting me to solve it using their method.
You quote the sine formula, but you did not say which angle in the picture is the A in the formula.what do you mean?