Verified answer

Time to fall vertically is independent of horizontal velocity, as in the other question.

Sqrt. (2h/g) = 3.03 secs.

In that time, the rock will travel (3.03 x 12) = 36.36m. from the base of the cliff.

Putting aside wind resistance and therefore terminal velocity, you need to calculate the time it takes for the rock to reach the ground, which is the time it takes to travel 45 meters accelerating at 32ft*s^2, or 9.7536m*s^2. Once you have the time it takes to hit the ground, then you take that number, in seconds, and multiply by 12. If terminal velocity is taken into account, the take it into account. I'm guessing it takes 2.5 to 3 seconds to hit the ground, just as a rough estimate.

Whats air resistance and wind speed and form of abject(rock)...?