Докажите тождество (cos^2 a ) / (tg a/2 - ctg - вопрос №8892387222142 от LoLLLLLLLLLLLLLLLL 23.03.2022 01:12

Question

Алгебра: Докажите тождество (cos^2 a ) / (tg a/2 - ctg a/2) = (-1/4 sin2a)

LoLLLLLLLLLLLLLLLL · Answer

Cos²a/(tga/2-ctga/2)=-1/4*sin2a1)tga/2-ctga/2=(sina/2*sina/2-cosa/2*cossa/2)/(sina/2*cosa/2)=(sina/2)²-(cosa/2)²/1/2(2sina/2*cosa/2=-cosa/1/2*sina=-2cosa/sina2)cos²a:(-2cosa/sina)=-1/2sina*cosa=-1/4(2sina*cosa)=-1/4*sin2a...