It is easy to find the missing angle since a triangle has 180 degrees and you know two of the angles. The missing angle is 90 - 57 = 33 degrees.
Now you know the missing angle is 33 degrees you can use the sine rule:
where side a is opposite angle A and the same for B and C
In other words and since then you can solve for the missing side a:
edit: the title is misleading if you want to find out the side...
Is your calculator in degrees mode?
Edit: if you think about it so the answer won't be more than 11 for sure. I'm confused as to how you get 57.98...