If your 3 yards up a tree your 9 feet up not 15 still another- [what if I were 6 yards (30ft) up in a tree] Better go back to school and forget theories and my guess is yes you missed something it was called Math just bustin ya good luck and just practice from the height you' ll be shooting from and you' ll have no problems. ( that you' ll have to solve with a pencil)