Question

If $co{s}^{-1}\frac{3}{5}-si{n}^{-1}\frac{4}{5}=co{s}^{-1}x$ then x equal to

• A. \N
• B. 1
• C. -1
• D. None of these

Answer 1

The correct option is B 1

We have
$co{s}^{-1}\frac{3}{5}-si{n}^{-1}\frac{4}{5}=co{s}^{-1}x$
$\Rightarrow si{n}^{-1}\left[\sqrt{1-\frac{a}{25}}\right]-si{n}^{-1}\frac{4}{5}=co{s}^{-1}x$
$\Rightarrow si{n}^{-1}\frac{4}{5}-si{n}^{-1}\frac{4}{5}=co{s}^{-1}x$
$\Rightarrow co{s}^{-1}x=0\Rightarrow x=cos0=1$
$\therefore x=1$