Question

Доказать тождество: 1/(tg(a)+ctg(a))=sin(a)*cos(a)

Answer 1

tga + ctga = sina/cosa + cosa/sina = (sin^2(a) + cos^2(a))/(cosa * sina) = 1 / (cosa * sina).

1/(tga + ctga) = cosa * sina.

Ч. Т. Д.