题目内容
(本小题满分12分)
求经过点
,且满足下列条件的直线方程:
(1)倾斜角的正弦为
; (2)与两坐标轴的正半轴围成的三角形面积为4。
求经过点

(1)倾斜角的正弦为

(1)
或
。(2)
。



本试题主要是考查了直线方程的求解的运用。
(1)根据设直线倾斜角为
,由
,得
,
分别得到直线的方程。
(2)设直线在
轴、
轴上的截距分别为
,可设直线方程
,由题意得
,解得
得到结论。
解:(1)设直线倾斜角为
,由
,得
,
……………………1分
当
时,由直线点斜式方程得
,即
;--3分
当
时,由直线点斜式方程得
,
即
;--------5分
综上,直线方程为
或
。----------6分
(2)设直线在
轴、
轴上的截距分别为
,可设直线方程
,由题意得
,解得
----10分
所以直线方程为
,即
。 ------12分
(1)根据设直线倾斜角为





分别得到直线的方程。
(2)设直线在






解:(1)设直线倾斜角为





……………………1分
当



当


即

综上,直线方程为


(2)设直线在






所以直线方程为



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