Simple,
using the Pythagorean Theorem...

You have the hypotenuse (C) and one of the legs (A)
So, plug in what you know...

144+

=400
Now,isolate


-144 -144
Leaving you with...

So, now,

, to find what b is..
b=16
Thus, your answer.
Y=sin(? when ?=0° the answer is 0
Y=0