Упростить.1)(1/sin^2a)-(ctg^2a)-(cos^2b)2)(ctg^2a-cos^2a)*((1/1cos^2a)-1)

   Приведем к общему знаменателю и сократим дроби:

   1) x = 1/sin^2(a) - ctg^2(a) - cos^2(b);

• x = 1/sin^2(a) - cos^2(a)/sin^2(a) - cos^2(b);
• x = (1 - cos^2(a))/sin^2(a) - cos^2(b);
• x = sin^2(a)/sin^2(a) - cos^2(b);
• x = 1 - cos^2(b);
• x = sin^2(b).

   2) y = (ctg^2(a) - cos^2(a)) * (1/cos^2(a) - 1);

• y = (cos^2(a)/sin^2(a) - cos^2(a)) * (1 - cos^2(a))/cos^2(a);
• y = cos^2(a)(1/sin^2(a) - 1) * sin^2(a)/cos^2(a);
• y = (1/sin^2(a) - 1) * sin^2(a);
• y = 1 - sin^2(a);
• y = cos^2(a).

   Ответ: 1) sin^2(b); 2) cos^2(a).