In a World Cup soccer match, Juan is running due north toward the goal with a speed of 7.70 relative to the ground. A teammate passes the ball to him. The ball has a speed of 13.3 and is moving in a direction of 30.5 east of north, relative to the ground.
a) what is the magnitude of the ball's velocity relative to Juan?
b) what is the direction of the ball's velocity relative to Juan?