tg (x - П/4) = sin (x - П/4) / cos (x - П/4) == ( sin(x) cos(П/4) - cos(x) sin(П/4) ) / ( cos(x) cos(П/4) + sin(x) sin(П/4) );sin (П/4) = cos (П/4) = sqrt(2) / 2;Сократим числитель и знаменатель на sqrt(2) / 2;Тогда:tg (x - П/4) = ( sin(x) - cos(x) ) / ( sin(x) + cos(x) );tg (x + П/4) = sin(x - П/4) / cos (x - П/4) == ( sin(x) cos(П/4) + cos(x) sin(П/4 ) ) / ( cos(x) cos(П/4) - sin(x) sin(П/4) ) == ( sin(x) + cos(x) ) / ( cos(x) - sin(x) );tg (x - П/4) - tg (x + П/4) == ( sin(x) - cos(x) ) / (sin(x) + cos(x) ) + ( sin(x) + cos(x)) / (sin(x) - cos(x) ) == ( (sin(x) - cos(x) )^2 + ( sin(x) + cos(x) )^2) / ( cos^2(x) - sin^2(x) ) == - ( 2sin^2(x) + 2cos^2(x) ) / ( cos^2(x) - sin^2(x) ) = - 2 / cos(2x);Ответ: tg(x - П/4) - tg(x + П/4) = - 2 / cos(2x);