Now, while up in that tree how do you know you are judging the hypotenuse of a right triangle? What if the tree isn't perpendicular to the ground? LOL.
I apparently have WAY too much time to think when I'm up there not seeing any deer.
Not perpendicular? Oh crap, let me recalculate and I'll write another 3 pages. [:@]
It helps to practice tree stand type shots
Right there is the most valuable advice that could ever be given.
Try it for yourself, and see. Use a rangefinder to check horizontal and angled distance so you start with seeing how big or little the difference is, and then take shots to see what the difference in drop is. The slower your arrows are, the more it will matter. Mine are only doing 220, so it can be a couple inches.