I have the question "Resolve the forces acting on the following objects into their vertical and horizontal components and thus find the vertical and horizontal components of their resultant force.
The solutions say that the answer should be:
And I know that I have to use trigonometry but I am not sure how the answer is achieved.
Extend the vertical line in the top figure might help.
The vertical upward force can be computed by
$$3-4 \cos(180 ^\circ-125^\circ)$$
The horizontal force towards the left can be computed by
$$4-4 \sin(180^\circ - 125 ^\circ)$$