Short answer: I don’t think any of these…
You know that it’s a right triangle so you can use trig functions.
You have an angle, the hypotenuse, and you need to find the opposite side
The trig function that incorporates all of these is Sin because sinx=o/h
So now just plug in numbers: sin(39)=x/16
Sin of 39 is about 0.96, so 0.96=x/16
x=15.4 which… isn’t… on there…
Well shoot