Question

Упростите выражение:

$frac{1}{1-tg^{2}alpha} - frac{1}{1-ctg^{2}alpha}$

Answer 1

1-tg^2a=cos2a/sin^2a

1-ctg^2a=-cos2a/cos^2a

sin^2a/cos2a+cos^2a/cos2a=1/cos2a

Answer 2

1-tg^2a=cos2a:sin^2a 1-ctg^2a=-cos2a:cos^2a sin^2a:cos2a+cos^2a:cos2a=1:cos2a