horzontal velocity and vertical acceleration are independent. and nuge, you should be ashamed of yourself, a budding physicist, for converting any of those numbers out of the metric system. also, horizontal velocity, in a perfect equation or a vacuum doesn't change, but with vane drag it sure does. you could have easily figured the distances using the good old pythagorean theorem. an object will gain an immediate vertical acceleration of 9.8 m/s2 no matter which direction it is fired in, but that's just it, vertical acceleration, straight down towards the center of the earth. it will gain no horizontal velocity as a result of this ever, period, they are independent. the distance should be measured from the ground to your target, so in your triangle you would use your 20 yd pin and not adjust as if it were a 21 yd shot. if you fire a rifle perfectly level with nothing in its way and drop a penny at the same time and from the same height, they will both hit the ground at exactly the same time. think about that.