If you want to hang a treetent with 3 straps between 3 trees finding the right lengths of the straps is very complicated.
The forces will be imbalance when the lengths arent correct and sleeping will not be comfortable.
Treetent Calculator gives you the optimal force balance of
tree-tents connected with 3 hatchets to 3 trees.
The only thing you need to know is the distance between the trees measured in cm or feet or something else like pineapples or oak leaves.