Question

помогите упростить и подробнее Буду признателен

Answer 1

(tg(α/2)-ctg(α/2))/(tg(α/2)+ctg(α/2))=
=(sin(α/2)/cos(α/2)-cos(α/2)/sin(α/2))/(sin(α/2)/cos(α/2)+cos(α/2)/sin(α/2))=
=(sin²(α/2)-cos²(α/2))/(sin(α/2)cos(α/2))/(sin²(α/2)+cos²(α/2))/(sin(α/2)cos(α/2))=
=-cosα/1=-cosα.