This paper applies geometric vector concept to derive the relations between double plane angle ( angle between two planes ) and planar angle when three planes intersects each other , and obtains eight formulae for working out the related angles and expanded dimensions on driver ' s cabs of material handling equipment 摘要動用幾何中向量的概念,推導出3個平面兩兩相交時,其二面角與平面角的關系,得出8個計算公式,可解決起重運輸機械駕駛室的有關角度和展開尺寸的計算。