@se_ven; no, because that assumes a constant force, whereas air resistance causes the force to be in rough inverse proportion to velocity. Also, if the building is very tall, the curvature of the earth comes into effect. Because the top of a building is further from the center of the earth than the base, it is moving faster with the rotation of the earth. Thus, a stone dropped with the same horizontal velocity as the top of the building will, when it reaches the bottom, be moving relative to the ground, and will land somewhat to the east of the building’s base. As the earth is curved, this also means that it will fall somewhat further than it otherwise would have; or at least, irregular terrain implies that the distance fallen is probably not the same as the height of the building. In fact, if the building is tall enough, it may go into orbit. This effect is lessened by air resistance, of course.
For those who can’t tell, I’m just having fun here. Just use trig as others have suggested.