Question

Let $f\left(x\right)=\sin x-x\cos x,x\in R$

The least positive value of $x$,for which $f\left(x\right)=0,$ lies in quadrant

• A. $I$
• B. $II$
• C. $III$
• D. $IV$

Answer 1

The correct option is C $III$

$f\left(x\right)=0\Rightarrow tanx=x$

(we can divide by $\cos x$, as $x=\frac{\pi }{2}$ does not satisfy $f\left(x\right)=0$.)
$\Rightarrow$ $x$ lies in the $3rd$ quadrant.