MCQ
$\mathop {\lim }\limits_{x \to 0} \frac{{{{\left( {1 - \cos \,2x} \right)}^2}}}{{2x\,\tan \,x - x\,\tan \,2x}}$ is
  • A
    $2$
  • B
    $ - \frac{1}{2}$
  • $-2$
  • D
    $  \frac{1}{2}$

Answer

Correct option: C.
$-2$
c
$\,\left( C \right)\,\,\,\,\,\,\mathop {\lim }\limits_{x \to 0} \frac{{{{\left( {1 - \cos 2x} \right)}^2}}}{{2x\tan x - x\tan 2x}}$

$\, = \,\mathop {\lim }\limits_{x \to 0} \frac{{{{\left( {{{\sin }^2}x} \right)}^2}}}{{2x\left( {x + \frac{{{x^3}}}{3} + \frac{{2{x^5}}}{{15}} + ....} \right) - x\left( {2x + \frac{{{2^3}{x^3}}}{3} + \frac{{{2^5}{x^5}}}{{15}} + ....} \right)}}$

             $\, = \mathop {\lim }\limits_{x \to 0} \frac{{4{{\left( {x + \frac{{{x^3}}}{{3!}} + \frac{{{x^5}}}{{5!}} - ....} \right)}^4}}}{{{x^4}\left( {\frac{2}{3} - \frac{8}{5}} \right) + {x^6}\left( {\frac{4}{{15}} - \frac{{64}}{{15}}} \right)}}$

             $ = \mathop {\lim }\limits_{x \to 0} \frac{{4{{\left( {1 + \frac{{{x^3}}}{{3!}} + \frac{{{x^5}}}{{5!}} - ....} \right)}^4}}}{{ - 2 + {x^2}\left( { - \frac{{60}}{{15}}} \right) + ......}}$

        (dividing numerator & denominator by ${{x^4}}$)

          $=2$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

What is the value of $ \lim_\limits{\text{x} \rightarrow 0}\frac{\text{x}^2\sec\text{x}}{\sin\text{x}}?$
If $A = \{2, 4, 6, 8, 10\}, B = \{1, 3, 5, 7, 9\},$ then $A - B =............$
The average weight of a group of $20$ boys was calculated to be $89.4\ kg$ and it was later discovered that one weight was misread as $78\ kg$ instead of $87\ kg.$ The correct average weight is:
How many words can be formed from the letters of the word $COURTESY$, whose first letter is $C$ and the last letter is $Y$
The minimum value of $(8sec^2 \theta + 2cos^2 \theta)$ is equal to :-
The probability of hitting a target by three marks men is $\frac{1}{2} , \frac{1}{3}$ and $\frac{1}{4}$ respectively. If the probability that exactly two of them will hit the target is $\lambda$ and that at least two of them hit the target is $\mu$ then $\lambda + \mu$ is equal to :-
For some $\theta \in\left(0, \frac{\pi}{2}\right),$ if the eccentricity of the hyperbola, $x^{2}-y^{2} \sec ^{2} \theta=10$ is $\sqrt{5}$ times the eccentricity of the ellipse, $x^{2} \sec ^{2} \theta+y^{2}=5,$ then the length of the latus rectum of the ellipse is
Ten ants are on the real line. At time $t=0$, the $k$ th ant starts at the point $k^2$ and travelling at uniform speed, reaches the point $(11-k)^2$ at time $t=1$. The number of distinct times at which at least two ants are at the same location is
The mean and standard deviation of $15$ observations were found to be $12$ and $3$ respectively. On rechecking it was found that an observation was read as $10$ in place of $12$ . If $\mu$ and $\sigma^2$ denote the mean and variance of the correct observations respectively, then $15\left(\mu+\mu^2+\sigma^2\right)$ is equal to$...................$
Area of the circle in which a chord of length $\sqrt 2 $ makes an angle $\frac{\pi }{2}$ at the centre is