rectangle and a circle have the same perimeter. Given that the length of the rectangle is 9 decimeters and the width is 6.7 decimeters, what is the area of the circle in square decimeters?
一个长方形和一个圆的周长相等．已知长方形的长是9分米，宽是6.7分米，圆的面积是多少平方分米？
<gadget id="calculator">9 + 6.7</gadget>
<output>15.7</output>

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

<gadget id="calculator">31.4 / 3.14 / 2</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>