Sorry, it looks like I misread the question. You can find the answer to that question by using the pythagorean theorem. The forumla for that is A squared+ B squared = C squared.

A- How high you are in the tree. We will just say 20'.
B- The distance you are from the deer. We will say 20 yards.
C- The answer of A and B after they have been added together.

First you have to find a common variable, which is feet. You are 20' up shooting 60' away. Plug in 20' for A, and 60' for B. You have to square A (you should get 400') and square B (you should get 3600'). You then add A and B (which is 400' + 3600') and get 4000'. The problem should look like this:

400' + 3600' = 4000'
You can verify this by adding 400' + 3600'. Does it equal 4000'? Yes it does, therefore it is correct.

Since we squared the problem, we have to find the square root of C. After square rooting 4000' you get 63.24'.

Since you want the answer in yards, you have to divide the answer, 63.24', by three. The answer is 21.08 yards. You have to compensate for 1.08 yards.

Conclusion- You do not have to aim any higher unless you shoot a bow like ButchA's!