What is the arc length of a sector with a radius of 4 cm and a central angle of 135°?
半径是4厘米，圆心角是135°的扇形所含的弧长为多少厘米．
<gadget id="calculator">135 * 3.14 * 4</gadget>
<output>1_695.6</output>

<gadget id="calculator">1_695.6 / 180</gadget>
<output>9.42</output>

<result>9.42</result>