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CBSE Class 12 Math 2018 Solved Paper

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Question : 1 of 29
Marks: +1, -0
Find the value of tan13cot1(3)\tan^{-1} \sqrt{3} - \cot^{-1}(-\sqrt{3})
Solution:  
tan13cot1(3)\tan^{-1} \sqrt{3} - \cot^{-1}(-\sqrt{3})
= tan13[πcot1(3)\tan^{-1} \sqrt{3} - [\pi - \cot^{-1}(-\sqrt{3})] (Since cot1\cot^{-1} (- x) = π - cot1\cot^{-1} (x))
= tan13π+cot1(3)\tan^{-1} \sqrt{3} - \pi + \cot^{-1}(-\sqrt{3})
tan13+cot1(3)\tan^{-1} \sqrt{3} + \cot^{-1}(-\sqrt{3}) - π
= π2π\frac{\pi}{2} - \pi (Since tan1\tan^{-1} (x) + cot1\cot^{-1} (x) = π2\frac{\pi}{2})
= - π2\frac{\pi}{2}
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