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If \sin^{-1}(x-1)+\cos^{-1}(x-3)+\tan^{-1}\left ( \frac{x}{2-x^{2}} \right )=\cos^{-1}k+\pi, then the value of k is equal to (Up to one decimal point)

Option: 1

1
 


Option: 2

-\frac{1}{\sqrt{2}}

 


Option: 3

0.7


Option: 4

2


Answers (1)

best_answer

 

Domains and Ranges of Inverse Trigonometric Functions -

For \sin ^{-1}x

Domain \epsilon \left [ -1, 1 \right ]

Range \epsilon \left [ -\frac{\pi }{2}, \frac{\pi }{2} \right ]

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Domains and Ranges of Inverse Trigonometric Functions -

For \cos ^{-1}x

Domain \epsilon \left [ -1, 1 \right ]

Range \epsilon \left [ 0, \pi \right ]

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Domains and Ranges of Inverse Trigonometric Functions -

For \tan ^{-1}x

Domain \epsilon R

Range \epsilon\left [ -\frac{\pi }{2},\frac{\pi }{2} \\ \right ]

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\sin ^{-1}(x-1)\Rightarrow -1\leq x-1\leq 1\Rightarrow 0\leq x\leq 2

\cos ^{-1}(x-3)\Rightarrow -1\leq x-3\leq 1\Rightarrow 2\leq x\leq 4

\tan ^{-1}\left ( \frac{x}{2-x^{2}} \right )\Rightarrow x\: \in \; R, x\neq \sqrt 2 ,

\therefore x=2

\sin ^{-1}(2-1)+\cos ^{-1}(2-3)+\tan ^{-1}\frac{2}{2-4}=\cos ^{-1}k+\pi

\sin ^{-1}1+\cos ^{-1}(-1)+\tan ^{-1}(-1)=\cos ^{-1}k+\pi

\frac{\pi}{2}+\pi-\frac{\pi}{4}=\cos ^{-1}k+\pi

\Rightarrow \cos ^{-1}k=\frac{\pi}{4}\Rightarrow k=\frac{1}{\sqrt{2}}

Posted by

Sanket Gandhi

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