Hi there! The fourth answer is correct.
In the picture we have to deal with facts:
1. The angle of 45°
2. The length of the opposite side
3. The length of the adjacent side.
Since we have to use the opposite and the adjacent side, we have to use the tangent of the angle. In a formula:
[tex] \tan( \alpha ) = \frac{opposite}{adjecent} [/tex]
Filling in this formula, brings us to the following answer.
[tex] \tan(45) = \frac{x}{1100} [/tex]
