$\cot ^{-1}\left(\frac{1}{2}\right)+\cot ^{-1}\left(\frac{1}{3}\right)=$ . . . . . . .

$\sin [\cot ^{ - 1}(\cos \tan ^{ - 1}x)] =$

સાબિત કરો કે $\sin ^{-1}(2 x \sqrt{1-x^{2}})=2 \cos ^{-1} x$,જ્યાં $\frac{1}{\sqrt{2}} \leq x \leq 1$.

જો $y = \sin^{-1}(2x\sqrt{1-x^2})$ હોય અને $-\frac{1}{\sqrt{2}} < x < \frac{1}{\sqrt{2}}$ હોય,તો $\frac{dy}{dx}$ શોધો.

જો $\operatorname{Tan}^{-1}\left[\frac{1}{1+1(2)}\right]+\operatorname{Tan}^{-1}\left[\frac{1}{1+(2)(3)}\right]+\operatorname{Tan}^{-1}\left[\frac{1}{1+(3)(4)}\right]+\cdots+\operatorname{Tan}^{-1}\left[\frac{1}{1+n(n+1)}\right]=\operatorname{Tan}^{-1} \theta$ હોય,તો $\theta=$

$2{\tan ^{ - 1}}\left[ {\sqrt {\frac{{a - b}}{{a + b}}} \tan \frac{\theta }{2}} \right] = $