Question

ПОМОГИТЕ ЛЮДИ СРОЧНО НАДО!!!! ПОЖАЛУЙСТА!!!! Упростите выражения:

Answer 1

$frac{1}{sin alpha -1} - frac{1}{sin alpha +1} = frac{sin alpha +1 -sin alpha +1 }{(sin alpha -1)(sin alpha +1)} =frac{2}{sin^{2} alpha-1} = frac{2}{-cos^{2} alpha} = - frac{2}{cos^{2} alpha} \ frac{sin^{2}alpha-1}{cos^{2}alpha-1} +tg alpha *ctgalpha = frac{-cos^{2}alpha}{-sin^{2}alpha} + 1= (frac{cosalpha}{sinalpha})^{2} + 1 = (ctgalpha)^{2} + 1 = frac{1}{sin^{2} alpha}$

$cos^{2} alpha-((ctgalpha)^{2} + 1 )*sin^{2} alpha = cos^{2} alpha-frac{1}{sin^{2} alpha}*sin^{2} alpha = \ =cos^{2} alpha-1= - sin^{2} alpha$

Answer 2

sina+1-sina+1               2                      2

=____________= ____________=  - __________

sin²a-1                         -cos²a                 cos²a

sin²a-1+cos²a-1            1     - 2           -1               1

________________= _______=   _______=_________

cos²a-1                               -sin²a      -sin²a           sin²a

cos²a- 1/sin²a*sin²a=cos²a-1=-sin²a