After cutting a circular piece of paper, put it together into an approximate rectangle with the width equal to the radius and the area unchanged. The perimeter of the rectangle is 16.56 cm. What is the area of the cut circular piece of paper in square cm?

After cutting a circular piece of paper, put it together into an approximate rectangle with the width equal to the radius and the area unchanged. The perimeter of the rectangle is 16.56 cm. What is the area of the cut circular piece of paper in square cm?

Let the radius of this circle be r. according to the meaning of the question, we can get: 2 × 3.14r + 2R = 16.56, & nbsp; & nbsp; 6.28r + 2R = 16.56, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 8.28r = 16.56, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; r = 2, 3.14 × 22, = 3.14 × 4, = 12.56 (square centimeter). Answer: the area of the paper is 12.56 square centimeter