Ответ:

Verified answer

Ответ:

a) 2tg^2a

б) 1

Объяснение:

a) 1-sin^4a-cos^4a/cos^4a = 1-sin^4a-(cos^2a)^2/cos^4a = (1-cos^2a)*(1+cos^2a)-sin^4a/cos^4a = (1+cos^2a-sin^2a)*sin^2a/cos^4a = (cos^2a+cos^2a)*sin^2a/cos^4a = 2sin^2a * cos^2a/cos^2a*cos^2a = 2tg^2a

б) 1/(1+tg^(2) a) + 1/(1+ctg^(2) а) = 1/(1+tg^(2) a) + 1/(1+1\tg^(2) а) = 1/(1+tg^(2) a) + 1/ ( (tg^(2) a+1)\tg^(2) а) = 1/(1+tg^(2) a) + tg^ (2) a/ ( 1+tg^(2) a) = (1+tg ^(2) a)\(1+tg^(2) a = 1