1)

$\sin^{-1}\frac{\sqrt{3}}{2}+\sin^{-1}\sqrt{\frac{2}{3}}$= 


A) $\sin^{-1}\frac{\sqrt{3}+\sqrt{2}}{2\sqrt{3}}$

B) $\pi-\sin^{-1}\left(\frac{\sqrt{3}+\sqrt{2}}{2\sqrt{3}}\right)$

C) $-\pi-\sin^{-1}\left(\frac{\sqrt{3}+\sqrt{2}}{2\sqrt{3}}\right)$

D) $\pi+\sin^{-1}\left(\frac{\sqrt{3}+\sqrt{2}}{2\sqrt{3}}\right)$

Answer:

Option B

Explanation:

We have, 

$\sin^{-1}\frac{\sqrt{3}}{2}+\sin^{-1}\sqrt{\frac{2}{3}}$

         $=\pi-\sin^{-1}\left[\frac{\sqrt{3}}{2}\sqrt{1-\left(\sqrt{\frac{2}{3}}\right)^{2}}+\frac{\sqrt{3}}{2}\sqrt{1-\left(\sqrt{\frac{3}{2}}\right)^{2}}\right]$

 As    0< $\frac{\sqrt{3}}{2}=0.866, \sqrt{\frac{2}{3}}=0.816 \leq$ 1   and

  $\left(\frac{\sqrt{3}}{2}\right)^{2}+\left(\sqrt{\frac{2}{3}}\right)^{2}=1.4167>1$

                   $[ \because   \sin^{-1} x+\sin^{-1}y=\pi-\sin^{-1}$

                 $x-\sqrt{1-y^{2}}+y\sqrt{1-x^{2}}, if 0<x,y\leq1$    and $x^{2}+y^{2} >1$]

    = $\pi-\sin^{-1}\left[\frac{\sqrt{3}}{2}\sqrt{1-\frac{2}{3}^{}}+\frac{\sqrt{2}}{3}\sqrt{1-{\frac{3}{4}}}\right]$

   = $\pi-\sin^{-1}\left[\frac{\sqrt{3}}{2}\sqrt{\frac{3-2}{3}^{}}+\frac{\sqrt{2}}{3}\sqrt{{\frac{4-3}{4}}}\right]$

      =$\pi-\sin^{-1}\left[\frac{\sqrt{3}}{2}{\frac{1}{\sqrt{3}}^{}}+\frac{\sqrt{2}}{\sqrt{3}}{\frac{1}{2}}\right]$

  $=\pi-\sin^{-1}\left[\frac{\sqrt{3}+\sqrt{2}}{2\sqrt{3}}\right]$