Calculating a projectiles angle required to hit object.

I'm trying to use the formula alt text

from http://en.wikipedia.org/wiki/Trajectory_of_a_projectile to work out the angle required to launch a projectile a known distance with the launch height not being the same as the targets. I'm not sure if I've coded it right because the result seems to be incorrect. Any help is appreciated.

var distance : float; //target distance
var height : float // launch height
var reqAngle : float;

 function Start()
 {
    RequiredAngle(distance, height);
 }
function RequiredAngle(x,y)
{
    reqAngle = Mathf.Atan(Mathf.Pow(velocity,2)
        +Mathf.Sqrt((Mathf.Pow(velocity,4)
        -(gravity*(Mathf.Pow(gravity*x,2)
        +Mathf.Pow(2*y*velocity,2)
        /gravity*x)))));    
}

The inner-most bracket expression says to take g and multiply it by x-squared and then add two times y times v-squared. In your code you are squaring gravity times x and two times y times v.

For more reference Check this link below :