题目

三棱锥S—ABC的三条侧棱两两垂直,且SA=1,SB=,SC=,则∠ABC的值为(    )A.30°                 B.45°                  C.60°                 D.120° 答案：答案:C解析:AB=,同理,BC=3,AC=.由余弦定理可得cos∠ABC=.∴∠ABC=60°.

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