A) \[-1\]
B) \[\sin 2\pi \]
C) \[\cos 2x\]
D) zero
Correct Answer: A
Solution :
\[y={{\tan }^{-1}}\left( \frac{\cos x-\sin x}{\cos x+\sin x} \right)\] \[y={{\tan }^{-1}}\left( \frac{1-\tan x}{1+\tan x} \right)\] \[\Rightarrow \] \[y={{\tan }^{-1}}\tan \left( \frac{\pi }{4}-2 \right)\] \[y=\frac{\pi }{4}-x\Rightarrow \frac{dy}{dx}=-1\]You need to login to perform this action.
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