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Question

cho d1:x-y-2=0 cat d2:x+2y-2=0tai I viet phuong trinh

$\Delta$ quaM(-1;1) cat d1,d2 lan luot la A, Bsao cho AB=3IA

thiensugacoi_95 · Answer 1 · 6/1/2013 8:46:53 AM

Ta tinh goc giua 2 duong thang

$d_{1}$ va

$d_{2}$

$cos\alpha =\pm \frac{1}{\sqrt{10}}$

$=>sin\alpha =\frac{3}{\sqrt{10}}$

Ap dung dinh ly ham sin cho tam giac ABI

$\frac{AB}{sin\alpha }=\frac{AI}{sin\beta }=>sin\beta =\frac{1}{\sqrt{10}}$ vs

$\beta$ la goc giua

$d_{1}$ va

$\Delta$

Tu do suy ra

$cos\beta =\pm \frac{3}{\sqrt{10}}$

Tiep theo la lap pt duong thang

$\Delta$ qua M(-1;1) va tao vs

$d_{2}$ goc

$\beta$

Bai toan co ban?

Trả lời 01-06-13 08:46 AM

thiensugacoi_95
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