Question

Помогите пож 423(3,5,2,4,6,8)

Answer 1

3) $frac{ctg(- beta )sinbeta}{cosbeta} = -ctg beta cdot tgbeta=-1$
5) $ctg alpha sin(- alpha )-cos(- alpha )=- frac{cos alpha }{sin alpha }cdot sin alpha -cos alpha =-2cos alpha$
2) $cos^2 alpha tg^2(- alpha )-1=cos^2 alpha cdot frac{sin^2 alpha}{cos^2 alpha} -1=sin^2 alpha-1=-cos^2 alpha$
4) $frac{1-tg(-x)}{sin x+cos(-x)} = frac{1+tgx}{sin x+cos x} = cfrac{1+ frac{sin x}{cos x} }{sin x+cos x} = frac{cos x+sin x}{cos x(sin x+cos x)} = frac{1}{cos x}$
6) $tg(-u)ctgu+sin^2u=-tgucdot ctgu+sin^2u=-1+sin^2u=-cos^2u$
8) $frac{tg(-x)+1}{1-ctgx} = frac{-tgx+1}{1-ctgx} =frac{tgx-1}{ctgx-1} = cfrac{ frac{sin x}{cos x} -1}{ frac{cos x}{sin x}-1} = cfrac{ frac{sin x-cos x}{cos x} }{ frac{cos x-sin x}{sin x}} =- frac{sin x}{cos x} =-tgx$