I used to know how to do this, but I forgot.[] You find the "legs" of the triangle to find the unknown side. This would be helpful for me because if I'm a few yards off, I will miss the kill zone. How do you do that? I think you do something like A2+B2=C2 devide by 2. I'm not sure though. That way I could see how high I am, and how far away the deer is from the ground and plug it in, and estimate how far the deer is at what angle.