PLEASE HELP!! Find the missing side and round to the nearest tenth.

Answer:
Hey there!
We have an angle of 51 degrees, and a hypotenuse of 16 units in length.
Thus, because the missing side is adjacent to 51 degrees, we can use Cosine 51= x/16, or Cosine 51 (16)=x=10.01
x=10.0 units.