9.C过O作ON⊥AB于N,过D作DM⊥ON于M,如图,则AN=BN=二AB=0.5(米),∠ONC=∠DMN=90°,.DC⊥AB,.∠DCN=90°,.四边形DCWM是矩形,.MN=CD=0.7米,DM=CN=BC+BN=1.20W2=r2-0.5D(米),设该圆的半径长为”米,由题意得,0M2=r2-1.22,解得OM=ON-0.7第9题答案图r=1.3OW=1.2,即该圆的半径长为1.3米,故选C.OM=0.5P