11.(2023•海淀区校级模拟)已知OOO是ΔABC\Delta ABCΔABC的外心,外接圆半径为2,且满足2AO→=AB→+AC→2\overrightarrow{AO}=\overrightarrow{AB}+\overrightarrow{AC}2AO=AB+AC,若BA→\overrightarrow{BA}BA在BC→\overrightarrow{BC}BC上的投影向量为34BC→\frac{3}{4}\overrightarrow{BC}43BC,则AO→⋅BC→=(\overrightarrow{AO}\cdot \overrightarrow{BC}=(AO⋅BC=( )))