Problem

In Exercise, use the method of Example 4. Distance betwee...

In Exercise, use the method of Example 4.

Distance between a Whale and a Lighthouse Debbie Glockner-Ferrari, a whale researcher, is watching a whale approach directly toward a lighthouse as she observes from the top of this lighthouse. When she first begins watching the whale, the angle of depression to the whale is . Just as the whale turns away from the lighthouse, the angle of depression is . If the height of the lighthouse is 68.7 m, find the distance traveled by the whale as it approached the lighthouse.