direction key方向键directionn.方向；指导；用法说明；趋势；目标；管理direction finder antenna测向器天线Directional seismic wave定向地震波Direction in Development发展趋势directional intersection方向交会法direction error revising方向校正directional oscillations方向摆动direction control damper航向控制阻尼器direction of exploration勘探方向directional presentation方向显示,指向性显示directional louds peaker指向扬声器

1. The bar directions are conveniently specified by direction cosines.
   杆的方向通常用方向余弦来表示。