解:连接AG并延长交BC于点H,∵点G是Rt△ABC的重心,∴BH=CH, AG AH = 2 3 ,∵GE∥BC,∴△AGE∽△AHC,∴ GE CH = AE AC = 2 3 ,设GE=2x,则CH=3x,BC=6x,∵GF:GE=1:2,∴GF=HF=x,∵四边形GECF是矩形,∴CE=GF=x,∴AC=3CE=3x,∴tan∠B= AC BC = 3x 6x = 1 2 .