B
baicachoem


giai pt : 1, [tex]3 - 4cos^2x=sin(2sinx+1)[/tex]
2, [tex]2sin^2x+cos2x=sinx[/tex]
3, [tex]sin3x+cos2x=1+2sinxcos2x[/tex]
chung minh : tan A/2 +tan B/2 +tan C/2 \geq[TEX]\sqrt{3}[/TEX]
2, [tex]2sin^2x+cos2x=sinx[/tex]
3, [tex]sin3x+cos2x=1+2sinxcos2x[/tex]
chung minh : tan A/2 +tan B/2 +tan C/2 \geq[TEX]\sqrt{3}[/TEX]
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