Divide a circle into several parts on average, and then put together an approximate rectangle. Measure the perimeter of this rectangle is 20.7 centimeters. What is the area of this circle in square centimeters?
把一个圆平均分成若干份，然后，拼成一个近似的长方形，量得这个长方形的周长是20.7厘米，这个圆的面积是多少平方厘米．
<gadget id="calculator">20.7 / 8.28</gadget>
<output>2.5</output>

<gadget id="calculator">3.14 * 2.5 * 2.5</gadget>
<output>19.625</output>

<result>19.625</result>