A surveyor measures the distance across a straight river by the following method: Starting directly across from a tree on the opposite bank, she walks d = 100 m along the riverbank to establish a baseline. Then she sights across to the tree. The angle from her baseline to the tree is θ = 35.0°. How wide is the river?

A surveyor measures the distance across a straight river by the following method: Starting directly across from a tree on the opposite bank, she walks d = 100 m along the riverbank to establish a baseline. Then she sights across to the tree. The angle from her baseline to the tree is θ = 35.0°. How wide is the river?