A rectangle and a circle have the same perimeter. It is known 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>