Given that the central angle of the sector is 120° and the radius is 3, what is the area of the sector?
已知扇形的圆心角为120°，半径为3，则这个扇形的面积是多少．
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">120 * 3.14 * 9</gadget>
<output>3_391.2</output>

<gadget id="calculator">3_391.2 / 360</gadget>
<output>9.42</output>

<result>9.42</result>