The central angle subtended by an arc is 72°, and the diameter of the circle is 10 cm, what is the length of the arc in cm?
一弧所对圆心角是72°，所在圆的直径是10厘米，则弧长是多少厘米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">72 * 3.14 * 5</gadget>
<output>1_130.4</output>

<gadget id="calculator">1_130.4 / 180</gadget>
<output>6.28</output>

<result>6.28</result>