Four coplanar forces act at the point O, as shown in the diagram. A force of 2N acts along the positive y-axis. A force of 3N acts at 30 degrees to the left of the positive y-axis. A force of 5N acts at 30 degrees to the right of the positive y-axis. A fourth force of 2N acts at right angles to the 5N force, below the positive x-axis. The forces $\mathbf{i}$ and $\mathbf{j}$ are of 1N magnitude in the directions of the x and y axes respectively.

Measure each direction anticlockwise from the positive $x$-axis. The 2N force along the $y$-axis is at $90^{\circ}$, the 3N force at $90^{\circ}+30^{\circ}=120^{\circ}$, the 5N force at $90^{\circ}-30^{\circ}=60^{\circ}$, and the fourth 2N force, drawn at right angles to the 5N force, at $60^{\circ}-90^{\circ}=-30^{\circ}$.

Resolving along $\mathbf{j}$:

$3\sin 120^{\circ}+2\sin 90^{\circ}+5\sin 60^{\circ}+2\sin(-30^{\circ})=\dfrac{3\sqrt{3}}{2}+2+\dfrac{5\sqrt{3}}{2}-1$

$=\dfrac{8\sqrt{3}}{2}+1=1+4\sqrt{3}=7,93$.