[Toán 11] Bài tập lượng giác

C

chuminhtuannghean

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C

chuminhtuannghean

thi co gi dau ma kho hieu sinbinh la ; sinx.sinx la vi minh ko biet viet binh phuong.trong do m la ẩn số.............
 
N

niemkieuloveahbu

[TEX]sin^2x + sin^2m + sin^2[x+m]=\frac{9}{4}[/TEX]
\Leftrightarrow[TEX] \frac{1-cos2x}{2}+\frac{1-cos2m}{2}+\frac{1-cos(2x+2m)}{2}=\frac{9}{4}[/TEX]
\Leftrightarrow[TEX]4cos^2(x+m)+4cos(x+m)cos(x-m)+1=0[/TEX]
\Leftrightarrow[TEX][2cos(x+m)+1]^2+sin^2(x-m)=0[/TEX]
\Leftrightarrow[TEX]\{cos(x+m)=\frac{-1}{2}\\sin(x-m)=0[/TEX]
Giải ngon nhé.:)>-:)>-
 
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