A square piece of paper with side length of 20 cm is cut down from the top 5 cm along the 45 ° angle to form a small square in the middle to calculate the area of the small square

A square piece of paper with side length of 20 cm is cut down from the top 5 cm along the 45 ° angle to form a small square in the middle to calculate the area of the small square

It's not easy to draw. Finally, the side length of the small square is 5 times the root 2. So the area is 50 square centimeters