Ответ:

Пошаговое объяснение:

6.8 . a) tgπ/4 + ctg5π/4 = 1 + ctg( π + π/4 ) = 1 + ctgπ/4 = 1 + 1 = 2 ;

б) сtgπ/3 * tgπ/6 = 1/√3 * 1/√3 = ( 1/√3 )² = 1/3 ;

в) tgπ/6 - ctgπ/6 = 1/√3 - √3 = ( 1 - (√3 )² )/√3 = ( 1 - 3 )/√3 = - 2/√3 ;

г) tg9π/4 + ctgπ/4 = tg( 2π + π/4 ) + 1 = tgπ/4 + 1 = 1 + 1 = 2 .