Let's use 40° as our angle for this problem. Since we have the adjacent side and need the hypotenuse, we will use the cosine trig in this problem.
cos(40°) = adjacent/hypotenuse = 16/x
cos (40°) = 16/x
x·cos (40°) = 16
x = 16/cos(40°)
x = 16/0.766
≈20.89 or E