Please Help

There isn't anything to  solve.....we just want to evaluate this :   tan (acos(3/x))

Let acos(3/x) = theta

So.....theta is an angle whose cosine = 3 / x

So.... using the  Pythagorean Theorem......y =  sqrt (x^2 - 3^2) = sqrt (x^2 - 9)

So..... tan (acos(3/x)) =  tan (theta)  =  y / x    =   sqrt (x^2 - 9) / 3