高等代数与解析几何习题解答_第二版_课后答案详解_陈志杰.pdf

§ 1 1. , ABCD−A B C D , E F BC 1 1 1 1 −−→ −−→ −→ −−→ −→ −→ −→ −→ −→ C D . AB = a , AD = b , AA = c . a , b , c 1 1 1 : −−→ −−→ −→ −−→ (1) AC ; (2) BD ; (3) AF ; (4) EF . 1 1 D1 F C1 A1 B1 D →− C c →− b E A →− B a 1 : (1) −−→ −−→ −−→ −−→ −−→ −−→ −−→ −−→ BC = AD, CC = AA , AC = AB + BC + CC , 1 1 1 1 −−→ −→ −→ −→ AC1 = a + b + c . −−→ −−→ −−→ (2) BD = BD + DD , 1 1 −−→ −−→ −−→ −→ −−→ −−→ −→ BD = AD − AB = b − a , DD = AA . 1 1 −−→ −→ −→ −→ BD1 = b − a + c . −→ −−→ −−→ −−→ (3) AF = AD + DD + D F ,