Final answer:
An airplane practicing turns around a point with a direct tailwind reaches its greatest bank when it is perpendicular to the wind direction.
Step-by-step explanation:
When an airplane is practicing turns around a point with a direct tailwind, it will reach its greatest bank when it is perpendicular to the wind direction.
The bank angle of the airplane affects the balance between the lift force and the weight of the airplane. In a turn, the airplane needs greater lift than necessary for level flight, and the vertical component of lift balances the weight while the horizontal component accelerates the plane. For example, if the tailwind is blowing from the north, the airplane will reach its greatest bank when it is facing east or west.