If the central angle of the sector is 47° and the radius is 15 cm, if the central angle is reduced to the original (1/4) and the area of the sector remains unchanged, how many centimeters is the radius at this time?
圆心角为47°，半径为15厘米的扇形，如果圆心角缩小到原来的(1/4)，而要使扇形的面积保持不变，那么这时的半径为多少厘米？
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>