A boat is towed toward a dock by a cable attached to a winch that stands 10 ft above the water level see figure Let 8 be the angle of elevation of the winch and let L be the length of the cable as the boat is towed toward the dock Complete parts a to c below b Compute de dL When L 50 ft When L 20 ft when L 50 20 and 11 ft de dL de dL 10 ft 0 0041 Round to four decimal places as needed Round to four decimal places as needed