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\(tan^{-1}\frac{1}{2}+tan^{-1}\frac{1}{3}\)=?A. \(\frac{\pi}{3}\)B. \(\frac{\pi}{4}\) C. \(\frac{\pi}{2}\) D. \(\frac{2\pi}{3}\)

Answer»

Correct Answer is (B) \(\frac{\pi}{4}\) 

Let , x = \(tan^{-1}\frac{1}{2}+tan^{-1}\frac{1}{3}\)

 Since we know that tan-1 x + tan-1 y = \(tan^{-1}\frac{x+y}{1-xy}\) 

⇒ tan-1 1 + tan-1 \(\frac{1}{3}\)=  tan-1\((\frac{\frac{1}{2}+\frac{1}{3}}{1-(\frac{1}{3}\times\frac{2}{3})})\)\(tan^{-1}1\) = \(\frac{\pi}{4}\)



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