Phương trình lượng giác.

H

hienzu

[TEX]tan(x-15).cot(x+15)=\frac{1}{3}[/TEX]
\Leftrightarrow[TEX]\frac{sin(x-15)}{cos(x-15)}.\frac{cos(x+15)}{sin(x+15)}=\frac{1}{3} [/TEX]
\Leftrightarrow[TEX]\frac{sin2x-sin30}{sin2x+sin30}=\frac{1}{3} [/TEX]
\Leftrightarrow[TEX]\frac{sin2x-\frac{1}{2}}{sin2x+\frac{1}{2}}=\frac{1}{3} (1)[/TEX]
Đặt sin2x=t (-1\leqt\leq1):)
[TEX](1)\Leftrightarrow \frac{t-\frac{1}{2}}{t+\frac{1}{2}}=\frac{1}{3} [/TEX]
Làm tiếp nhé.................;)
 
You must log in or register to reply here.
Top Bottom