Two mountain bikers leave from the same parking lot and head in opposite directions on two different trails. The first rider goes 8 km due East, then rides due south for 15 km. The second rider goes 8 km due West, then changes direction and rides 20 degrees west of due north for 15 km. (See the picture below.) Both riders have been traveling for 23 km, but when they stopped, which one was further away from the parking lot?