In order to find an expression for z, we can use the sine and cosine relations of the angle 50°.
The sine is equal to the opposite leg over the hypotenuse, and the cosine is equal to the adjacent leg over the hypotenuse.
So we have:
[tex]\begin{gathered} \sin50°=\frac{x}{z}\\ \\ z=\frac{x}{\sin50°}\\ \\ \\ \\ \cos50°=\frac{y}{z}\\ \\ z=\frac{y}{\cos50°} \end{gathered}[/tex]
Therefore the correct option is the second one.
