1. Two forces F1 and F2 act on a particle. The force F1 is parallel to the vector (i + j) and the force F2 is parallel to the vector (i +2j). Given that the resultant R of these two forces is of magnitude 15N and parallel to the vector (3i + 4j), find the magnitude of F1 and the magnitude of F2.
I have found the vector of the resultant R to be (9i + 12j), but I don't know how to find the magnitudes of F1 and F2.