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nsnk_114


giup' to' bai` nay` @-)
tgx-3cotx=4.(sinx+can 3.cosx)
bai` nay` nua~
4sin^3x.sin3x+4cos^3x.cos3x=3
tgx-3cotx=4.(sinx+can 3.cosx)
bai` nay` nua~
4sin^3x.sin3x+4cos^3x.cos3x=3
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