On a coordinate plane, a line goes through points (0, 1) and (3, negative 1).
Consider the graph of the line.

Using the rise/run counting method, the slope of the line is .

From the top of a tree a bird looks down on a field mouse at an angle of depression of 50°. if the field mouse is 40 meters from the base of the tree, find the vertical distance from the ground to the bird's eyes.