You can figure yardage out using the Pythagorean Theorem a2 + b2 = c2

For example if your treestand is 15 ft high (a2)
A tree from the base of your tree is 20 yards or 60 feet (b2)

Then you would square 15' /15x15=225'
Then you would square 60'/ 3600'
Add Those 225'+3600'=3825'
c2=3825'
Now find the square root of that 3825' squared is 62' (rounded)
3 divided into 62'=20.6 yards

Thats how you find actual yardage assuming that the ground is fairly level.