[SOLVED] formula for curve path urgently needed

Hi,
I'm building a game based on tank wars.
The enemy tank ('computer') knows where the player's tank is, and the distance and the direction it has to fire to hit the player's tank in a straight line.

I want the 'computer's' tank to be able to fire at the player's tank and hit it, but for the missile to move on a curved path not a straight line.

Can anyone provide me with a foolproof and ideally simple formula for this?

I figured that because I know the average velocity surely I can find a formula that creates a curved path based on the given velocity so that the curved path and straight path intersect at the target at the same time, but it appears to beyond me.

For anyone interested, I'm building it in Flash.
Thanks for your help and for saving my brain!