Question

cos(90+a)tg(270+a)/cos(180-a)sin(90-a) упростить

Answer 1

$frac{cos(90+a)*tg(270+a)}{cos(180-a)sin(90-a)}= frac{-sina*(-ctga)}{-cosa*cosa}=\\=- frac{sina*cosa}{cos^2a*sina}=- frac{1}{cosa}$

Answer 2

$frac{cos(90+a)tg(270+a)}{cos(180-a)sin(90-a)} = frac{-sina*(-ctga)}{-cosacosa} = \ \ =- frac{sina* frac{cosa}{sina} }{cosa*cosa} = -frac{cosa}{cosa*cosa} =- frac{1}{cosa}$