2-3刚体的平面平行运动 J cos 8 ORMA C coSB lcos 6=30° an=-(812/3√3 o=(u? sin 8/12 cos 0)k§2-3 刚体的平面平行运动 j l u j l l u j l aB          3 2 2 2 2 2 cos cos cos cos = − = −  = −  = 30 a u l j B   (8 3 3 ) 2 = − 1 aB sin  = a u l k    ( sin cos ) 2 2 3  =  