Lượng giác khó

T

trantien.hocmai

16sinxcos4x+1=3(tanx+tan2x)+tanx.tan2x16sinxcos4x+1=\sqrt{3}(tanx+tan2x)+tanx.tan2x
↔16sinxcos4x+1=3.sinxcos2x+sin2xcosxcosxcos2x+sinxsin2xcosxcos2x \leftrightarrow 16sinxcos4x+1=\sqrt{3}.\frac{sinxcos2x+sin2xcosx}{cosxcos2x}+\frac{sinxsin2x}{cosxcos2x}
↔16sinx.cosx.cos2x.cos4x+cosx.cos2x=3sin3x+sinx.sin2x \leftrightarrow 16sinx.cosx.cos2x.cos4x+cosx.cos2x=\sqrt{3}sin3x+sinx.sin2x
↔8sin2x.cos2x.cos4x−3sin2x=sinx.sin2x−cosx.cos2x \leftrightarrow 8sin2x.cos2x.cos4x-\sqrt{3}sin2x=sinx.sin2x-cosx.cos2x
↔4sin4x.cos4x−3sỉnx+cosx.cos2x−sinx.sin2x=0 \leftrightarrow 4sin4x.cos4x-\sqrt{3}sỉnx+cosx.cos2x-sinx.sin2x=0
↔2sin8x−3sin3x+cos3x=0 \leftrightarrow 2sin8x-\sqrt{3}sin3x+cos3x=0
đến đây thì dễ rồi nhá
 
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