For this case we have that by definition of trigonometric relations of a rectangular triangle, that the cosine of an angle is given by the leg adjacent to the angle on the hypotenuse of the triangle. Then, according to the figure we have:
[tex]cos (53) = \frac {18} {x}[/tex]
Clearing x:
[tex]x = \frac {18} {cos (53)}\\x = \frac {18} {0.60181502}\\x = 29,9095226969[/tex]
Rounding:
[tex]x = 29.91[/tex]
Answer:
29.91
