The first image below shows force F1 and the axes.
Answer: [tex](F_{1})_{u}=[/tex] 3.62 kN
Explanation: The second figure below express the parallelogram method to calculate the u component of force F1.
The Parallelogram Method is a method to determine resultant force and is applied as described in the question above.
With the three components, [tex]F_{1},(F_{1})_{u}[/tex] and [tex](F_{1})_{v}[/tex] and angles, it can be used the Law of Sines, which states:
[tex]\frac{a}{sin\alpha} =\frac{b}{sin\beta} =\frac{c}{sin\theta}[/tex]
i.e., there is a relation of proportionality between an angle and its opposite side.
For the triangle below:
[tex]\frac{u}{sin30} =\frac{F_{1}}{sin105}[/tex]
[tex]u=F_{1}\frac{sin(30)}{sin(105)}[/tex]
[tex]u=7\frac{0.5}{0.966}[/tex]
u = 3.62
The magnitude of the component acting along the u-axis is 3.62kN.