(本小題滿分13分)
已知三點A(3,0),B(0,3),C
,
.
(1)若
,求角
;
(2)若
,求
的值.
解:(1) ∵![]()
···························· 2分
由![]()
得
········································ 4分
整理得![]()
∴
····························································································· 6分
∵
∴
·································································· 7分
(2) ∵![]()
∴
····························································· 8分
即
····················································································· 9分
∴
∴
················································································· 10分
∴
································· 13分
解析
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