题目如图,是某供水管道的截面图,里面尚有一些水,若液面宽度AB=8cmAB=8cmAB=8cm,半径OC⊥ABOC\bot ABOC⊥AB于DDD,液面深度CD=2cmCD=2cmCD=2cm,则该管道的半径长为( )A.6cm6cm6cmB.5.5cm5.5cm5.5cmC.5cm5cm5cmD.4cm4cm4cm知识点:垂径定理的应用章节:图形的性质 / 圆