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1.Relation and Function
medium
જો $f(x) = \sin \log x$, તો $f(xy) + f\left( {\frac{x}{y}} \right) - 2f(x).\cos \log y =$
A
$1$
B
$0$
C
$-1$
D
$\sin \log x.\cos \log y$
Solution
(b) $f(xy) = \sin \log xy = \sin \,(\log x + \log y)$…..$(i)$
$f(x/y) = \sin \log (x/y) = \sin \,(\log x – \log y)$…..$(ii)$
$\therefore \,\,f(xy) + f(x/y) = 2\,\sin \log x\cos \,\,\log y$
Hence required value of the function is
$2\,\sin \,\,\log x\,\cos \,\log y – 2\,\sin \,\log x\,\cos \,\log y = 0$.
Standard 12
Mathematics