Mathematic Problems
1+ctg 2x·ctg xtgx + ctg x
1+ctg 2x·ctg xtgx + ctg x
=1+cos 2xsin 2x·cos xsin xsin xcos x +cos xsin x
=sin 2x·sin x+cos 2x·cosxsin 2x·sin xsin2x+cos2xsin x·cos x
=cos 2x-xsin 2x·sin x1sin x·cos x
=cos xsin 2x·sin x1sin x·cos x
=sin x·cos2xsin 2x·sin x
=sin x·cos2x2sin x·cos x·sin x
=sin x·cos2x2sin x·cos x·sin x
=cos x2sin x
=12cos xsin x
=12ctg x
sin2α=2·sinα·cosα
sin2α=2·sinα·cosα
sin2α=2·sinα·cosα
1+ctg 2x·ctg xtg x + ctg x=12·ctg x