In a circle with a radius of 3 cm, what is the length of the arc subtended by a central angle of 60 degrees?
在半径为3cm的圆中，60度的圆心角所对的弧长为多少cm．
<gadget id="calculator">60 * 3.14 * 3</gadget>
<output>565.2</output>

<gadget id="calculator">565.2 / 180</gadget>
<output>3.14</output>

<result>3.14</result>