Question

\(\frac{sin2a-c\text{os}2a}{sin2a-c\text{os}2a}=tan4a-\frac{1}{c\text{os}4a}\)

Answer 1

\(\frac{sin2a-cos2a}{sin2a+cos2a}=\frac{\left(sin2a-cos2a\right)^2}{\left(sin2a+cos2a\right)\left(sin2a-cos2a\right)}\)

\(=\frac{sin^22a+cos^22a-2sin2a.cos2a}{sin^22a-cos^22a}=\frac{1-sin4a}{-cos4a}\)

\(=-\frac{1}{cos4a}+\frac{sin4a}{cos4a}=tan4a-\frac{1}{cos4a}\)

Answer 2

Đề ko đúng kìa bạn, vế trái tử mẫu giống nhau (bằng 1 luôn còn gì)