Good question!
Since we know the value of the hypotenuse and we want to find the value opposite of the angle given, We will use Sine.
First Step: write out the equation Sin(40)= c/15
Second Step: punch in Sin(40) (MAKE SURE YOUR CALC IS IN DEGREE MODE!!!!!) in your calculator and then multiply it by 15
(Sin(40)) x 15 = c
Final Step: after multiplying them together you'll get an answer of 9.64!
So the answer is the second one! hope I helped (:
