Answer:
See answer below
Explanation:
You are missing data such as the angle of the boat next to Dolores. I found an exercise similar to this, and I'm going to show it here and use the missing data to show you how to do it:
Dolores is on a bridge that is 45 feet above a lake. She sees a boat at a 30 degree angle of depression. What is Dolores' approximate horizontal distance from the boat?
According to that, I will use the angle of 30° to do this, but the distance of 42 feet.
Now, we can see this as a triangle. Dolores is on a bridge 42 feet above a lake, this 42 feet distance should be one side of the triangle (The vertical forming the 90° angle), and the boat that is on the lake, is seen with an angle of 30°. So the distance of the boat, to the spot where dolores is, under the bridge would be the horizontal side.
With this, we have the opposite side (a) and the adyacent side (b) of the triangle, and we have the angle, therefore:
tanα = a/b
Replacing we have:
tan30° = 42/b
b = 42 / tan30°
b = 72.75 feet
Hope this helps