2-3刚体的平面平行运动 6=30° i2=(/3 (2)用基点法求a g=×AB+ox(O×AB) a,=0×AB =O×(O×AB) a cos e=0×(o×AB)=02§2-3 刚体的平面平行运动  = 30 v u j B   = −( 3) （2）用基点法求 B a  ( ) ⎯→ ⎯→ aB = AB+  AB      ⎯→ a = AB    1 ( ) 2 ⎯→ a =  AB    a AB l B 2 cos = ( ) =  