Answer:
Only cosine include both hypotenuse and adjacent. We need both of them because those are 2 side that have numbers/letters.
So cos(28) = 11/x
Multiply by x
Then you'll get xcos(28) = 11
Do oposite cosine and you'll get
x = 11*opposite cos(28)
opposite cosine means cos^-1
thats approx. equal to 12.46 units