A rectangle and a circle have the same perimeter. Given that the length of the rectangle is 10 cm and the width is 5.7 cm, what is the area of the circle?
一个长方形和一个圆的周长相等．已知长方形的长是10厘米，宽是5.7厘米，圆的面积是多少．
<gadget id="calculator">10 + 5.7</gadget>
<output>15.7</output>

<gadget id="calculator">15.7 * 2</gadget>
<output>31.4</output>

<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">31.4 / 6.28</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>