Cut a square sheet of iron with a side length of 4 decimeters into the largest circle, and the area of the cut part is half of the square area______ %.

Cut a square sheet of iron with a side length of 4 decimeters into the largest circle, and the area of the cut part is half of the square area______ %.

[4 × 4-3.14 × (4 △ 2) 2] / (4 × 4), = [16-12.56] / - 16, = 3.44 △ 16, = 21.5%; answer: the area of the cut part is 21.5% of the square area; so the answer is: 21.5