T
tranodoi_92


1.$3cos^2 2x+3sin^2 x+cos^2 x=0$
2.$3sin^4 x+5cos^4 x-3=0$
3.$(2sinx-cosx)(1+cosx)=sin^2 x$
4.$tan(x-15^o)cot(x+15^o)= 1$
2.$3sin^4 x+5cos^4 x-3=0$
3.$(2sinx-cosx)(1+cosx)=sin^2 x$
4.$tan(x-15^o)cot(x+15^o)= 1$
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