A sector with a central angle of 120° has an area equal to the area of a parallelogram with a base of 6 cm and a height of 6.28 cm. Find the radius of the sector.
一个圆心角为120°的扇形，它的面积等于一个底是6厘米，高6.28厘米的平行四边形的面积，求扇形的半径．
<result>6</result>