A
angellove_18


Cmr:
a,$sin(2x+\frac{n}{3}).cos(x-\frac{n}{6})$.$cos(2x+\frac{n}{3})$.$cos(\frac{2n}{3}-x)=cosx$
[TEX]b,[/TEX]$tan^2x+cot^2x=\frac{6+2cos4x}{1-cos4x}$
a,$sin(2x+\frac{n}{3}).cos(x-\frac{n}{6})$.$cos(2x+\frac{n}{3})$.$cos(\frac{2n}{3}-x)=cosx$
[TEX]b,[/TEX]$tan^2x+cot^2x=\frac{6+2cos4x}{1-cos4x}$
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