What is the preferred form of the expression sin(arctan(8/(3x)))?
1) sin(arctan(8/(3x)))
2) sin(arctan(3x/8))
3) sin(arctan(3x/8)) / √(1 + (3x/8)²)
4) sin(arctan(8/(3x))) / √(1 + (8/(3x))²)