Divide a circle into 1000 identical small sectors on average, cut and piece together the approximate rectangle whose perimeter is 10 cm longer than the original circle, what is the area of this rectangle in square centimeters.
将一个圆平均分成1000个完全相同的小扇形，割拼成近似的长方形的周长比原来圆周长长10厘米，这个长方形的面积是多少平方厘米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 5 * 1 * 5</gadget>
<output>78.5</output>

<result>78.5</result>