Cut the largest square on a circular paper with a diameter of 10 cm. What is the area of the square?

Cut the largest square on a circular paper with a diameter of 10 cm. What is the area of the square?

The diagonal of the largest square is the diameter of the circle
That is to say, two times the root of the side length is the perimeter
So the area of a square is the square of the side length,
Then s = [1 / radical 2) * 10] ^ 2 = 50