Answer:
x = 10.1
Explanation:
The function SINE stands for Opp. / Hyp. the function that should be used is COSINE. We now know that cos(39) = x/13 and using a calculator we can substitute for cos(39).
Make sure your calculator is in degrees when plugging into your calculator so you don't use radians.
We get 0.777145961457 = x/13 now since we have substituted we can multiply both sides of the equation to get 10.1028974989 = x. When rounded, it is 10.1 units.