$\int \frac{\cos 2 x}{\cos x+\sin x} d x$ is equal to
Answer & explanation
Correct answer: option 3
$\int \frac{\cos 2 x}{\cos x+\sin x} d x=\int \frac{(\cos x+\sin x)(\cos x-\sin x)}{\cos x+\sin x} d x=\sin x+\cos x+c$
Hence (3) is the correct answer.