Answer
$\theta = 36.3°$
$\phi = 26.4°$
Work Step by Step
We are given the modules of F1, F2, F and the direction of the last. We are asked the angles of the other forces within the x axis.
Applying the law of cosines, we know that
$40^{2} = 30^{2} + 60^{2} - 2 \times 30 \times 60 \times \cos (\theta)$
$\theta = 36.34° \approx 36.3°$
And also
$30^{2} = 40^{2} + 60^{2} - 2 \times 40 \times 60 \times \cos (\phi)$
$\phi = 26.38° = 26.4°$
