Divide a circle evenly into several parts and assemble it into a parallelogram. The perimeter of the parallelogram is 49.68 decimeters. Find the area of this circle?
把一个圆平均分成若干份后拼成接近一个平行四边形，平行四边形的周长是49.68分米．求这个圆的面积？
<result>12.56</result>