Honeybee waggle dance.
Imagine a patch of flowers that is 1500 meters from a hive, at an angle 40 to the right of the sun. When a forager returns, it dances in a figure 8 pattern. In this case, the angle between a bee's "straight run" and a vertical line is 40. The length of the straight run portion of the dance translates into distance from the hive to the food source.