(本小题满分12分) 某几何体的直观图与三视图如下,其中主视图、俯视图都是直角三角形,左视图是等边 三角形. (Ⅰ)证明:ABCD; (Ⅱ)求该几何体的体积. 答案:解:(I)由三视图知三棱锥A-BCD中,面ABC⊥面BCD, ∠BCD=90°,AC=CD=BC, ……………4分 面ABC⊥面BCD, 面ABC∩面BCD=BC,∵CD⊥BC,∴CD⊥面ABC. ∵AB面ABC∴CD⊥AB. ……………8分 (II)三棱锥A-BCD的体积为. ………12分
“I’d like to express my thanks to those
____ help my husband would have been killed in the accident” said the woman on
TV.
A.who
B.with
their
C.with whose D.without whose