Aiden and May come to a river and notice a tree on the opposite bank. Separately

Aiden and May come to a river and notice a tree on the opposite bank. Separately

Aiden and May come to a river and notice a tree on the opposite bank. Separately they decide to place rocks (indicated with dots) on their side of the river to try to calculate the river’s width.
They then measure the distances between some pairs of rocks, as shown: