а) cos^2ttg^2t - sin^2tcos^2t = cos^2t(tg^2t - sin^2t) = cos^2tsin^2t
б) 1 - сos^2t + tg^2tcos^2t = sin^2t + tg^2tcos^2t
в) (1 - sin^2t)(tg^2t + 1) = cos^2t(tg^2t + 1)
г) (1 - cos^2t)(ctg^2t + 1) = sin^2t(ctg^2t + 1)
а) cos^2ttg^2t - sin^2tcos^2t = cos^2t(tg^2t - sin^2t) = cos^2tsin^2t
б) 1 - сos^2t + tg^2tcos^2t = sin^2t + tg^2tcos^2t
в) (1 - sin^2t)(tg^2t + 1) = cos^2t(tg^2t + 1)
г) (1 - cos^2t)(ctg^2t + 1) = sin^2t(ctg^2t + 1)