The area of the fan is 31.4 square centimeters, the area of the circle it is in is 157 square centimeters, what is the central angle of the fan.
扇形的面积是31.4平方厘米，它所在圆的面积是157平方厘米，这个扇形的圆心角是多少度．
<gadget id="calculator">31.4 / 157</gadget>
<output>0.2</output>

<gadget id="calculator">360 * 0.2</gadget>
<output>72</output>

<result>72</result>