Solve the all parts of given question:
Question: A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant the receiver is 16.1 m from the quarterback. The receiver should run in the direction opposite to that in which the football is travelling. The receiver should run in the direction the football is traveling.
Part A: In what direction should the receiver run in order to catch the football at the level at which it was thrown?
Part B: With what constant speed should the receiver run in order to catch the football at the level at which it was thrown?
Please explain clearly with details so that I can follow.