1/ $sin^{2}(2x+\pi /3) +sin2x +2cos2x=3$
2/ $cos^{2}x + cos^{2}2x + cos^{2}3x +cos^{2}4x =3/2$
3/ $cos^{2}x + cos^{2}2x + cos^{2}(\pi /3 -3x) =7/4$
4. $cos3x +cos7x = 2sin^{2}(\pi /4 +5x/2) -2cos^{2}(9x/2) $
5/ $tanx + tan2x+tan3x=tan6x$
1/ $sin^{2}(2x+\pi /3) +sin2x +2cos2x=3$
2/ $cos^{2}x + cos^{2}2x + cos^{2}3x +cos^{2}4x =3/2$
3/ $cos^{2}x + cos^{2}2x + cos^{2}(\pi /3 -3x) =7/4$
4. $cos3x +cos7x = 2sin^{2}(\pi /4 +5x/2) -2cos^{2}(9x/2) $
5/ $tanx + tan2x+tan3x=tan6x$
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