Man, this can get complicated, but let's keep it simple. Line of sight distance from a tree isn't "actual yardage." The correct yardage is from the base of the tree to your target. I don't know all the physics involved, but it's got to do w/ that triangle thing.

BUT, the single most reason people shoot high out of a treestand is this. They drop their bowarm to get on target instead of bending at the waist.