two racing boats set out from the same dock and speed away at the same constant speed of 115 km/h for half an hour (0.500 h), the blue boat headed 27.6° south of west, and the green boat headed 37.9° south of west. during this half-hour (a) how much farther west does the blue boat travel, compared to the green boat, and (b) how much farther south does the green boat travel, compared to the blue boat? express your answers in km.