sin(-a) = - sina
cos(-a) = cosa
tg(-a) = - tga
ctg(-a) = - ctga
Применяем формулы приведения:а) sin( α - 90° ) = - sin( 90° - α ) = - cosαб) ctg( α - π ) = - ctg( π - α ) = - ( - ctgα ) = ctgαв) ctg( α - 360° ) = - ctg( 360° - α ) = - ( - ctgα ) = ctgαг) tg( - α + 270° ) = tg( 270° - α ) = ctgαд) sin²( 180° + α ) = sin²αе) cos²( 270° - α ) = ( - sinα )² = sin²αж) tg²( 90° + α ) = ( - ctgα )² = ctg²αз) ctg²( 360° - α ) = ( - ctg( 360° - α ) )² = ( - ( - ctgα ) )² = ctg²αи) sin³( 270° + α ) = ( - cosα )³ = - cos³α
