Question

 решите пожалуйста ,очень нужно)

Answer 1

$sin^2t+cos^2t=1; ; to ; ; sin^2t=1-cos^2t\\\frac{sin^2t+cos^2t}{tg^2tcdot cos^2t}-frac{cos^2t}{1-cos^2t}=frac{1}{frac{sin^2t}{cos^2t}cdot cos^2t}-frac{cos^2t}{sin^2t}=frac{1}{sin^2t}-frac{cos^2t}{sin^2t}=\\=frac{1-cos^2t}{sin^2t}=frac{sin^2t}{sin^2t}=1$

Answer 2

1÷sin²t/cos²t×cos²t-cos²t÷sin²t=1÷sin²t-ctg²t=1+ctg²t-ctg²t=1
1=1
тотожність доведено