34.(2022•宁波模拟)在ΔABC\Delta ABCΔABC中,点OOO、点HHH分别为ΔABC\Delta ABCΔABC的外心和垂心,∣AB∣=5\vert AB\vert =5∣AB∣=5,∣AC∣=3\vert AC\vert =3∣AC∣=3,则OH→⋅BC→=\overrightarrow{OH}\cdot \overrightarrow{BC}=OH⋅BC=[ 8 ].