How to calcuate this without using a calculator
- Thread starter aruwin
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- Nov 24, 2012
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I would use the identities:
\(\displaystyle \tan^{-1}(-x)=-\tan^{-1}(x)\)
\(\displaystyle \tan^{-1}(x)+\cot^{-1}(x)=\dfrac{\pi}{2}\)
\(\displaystyle \cot^{-1}(x)=\tan^{-1}\left(\dfrac{1}{x} \right)\)
Can you put these together to obtain a solution?
\(\displaystyle \tan^{-1}(-x)=-\tan^{-1}(x)\)
\(\displaystyle \tan^{-1}(x)+\cot^{-1}(x)=\dfrac{\pi}{2}\)
\(\displaystyle \cot^{-1}(x)=\tan^{-1}\left(\dfrac{1}{x} \right)\)
Can you put these together to obtain a solution?