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3.Trigonometrical Ratios, Functions and Identities
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The value of $tan^{-1} (\frac{sin2 -1}{cos2})$ is equal to:-
A
$\frac{\pi}{2} - 1$
B
$2 - \frac{\pi}{2}$
C
$1- \frac{\pi}{4}$
D
$ \frac{\pi}{4}-1$
Solution
$\tan ^{-1}\left[\frac{2 \sin 1 \cos 1-\cos ^{2} 1-\sin ^{2} 1}{\cos ^{2} 1-\sin ^{2} 1}\right]$
$=-\tan ^{-1} \frac{\cos 1-\sin 1}{\cos 1+\sin 1}$
$=-\tan ^{-1} \tan \left[\frac{\pi}{4}-1\right]$
$=1-\frac{\pi}{4}$
Standard 11
Mathematics