The inner circle is inscribed in the square, and the square is inscribed in the outer circe. If the area of the outer circle is 256(pi) square millimeters, find the area of the inner circle.

(here there is a picture of a large circle, that holds a square whose corners touch the circle, and a smaller circle that fits inside the square)

there are 4 multiple choice answeres..

basically i already know that the answer is 128(pi) mm squared..but i have NO idea why

so PLEAAASEE just give me the steps.. thank you so much!