MCQ
$\int_0^{\pi /2} {x\cot x\,dx} $ equals
  • A
    $ - \frac{\pi }{2}\log 2$
  • $\frac{\pi }{2}\log 2$
  • C
    $\pi \log 2$
  • D
    $ - \pi \log 2$

Answer

Correct option: B.
$\frac{\pi }{2}\log 2$
b
(b) $I = \int_0^{\pi /2} {x\cot x\,dx} $

Integrating by parts, we get 

$[x(\log \sin x)]_0^{\pi /2} - \int_0^{\pi /2} {\log \sin x\,dx} $

$I = - \left( { - \frac{\pi }{2}\log 2} \right) = \frac{\pi }{2}\log 2$.

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

Let $a = 2i - j + k,\,\,b = i + 2j - k$ and $c = i + j - 2k$ be three vectors. A vector in the plane of $ b $ and $c $ whose projection on $a$ is of magnitude $\sqrt {2/3} $ is
Evaluate $\left|\begin{array}{cc}x & x+1 \\ x-1 & x\end{array}\right|$
Area of the region bounded by the curve $y=e^x$ and lines $x=0$ and $y=e$ is

$(A)$ $e-1$ $(B)$ $\int_1^e \ln (e+1-y) d y$ $(C)$ $e-\int_0^1 e^x d x$ $(D)$ $\int_1^r \ln y d y$

If $\text{f(x)}=\begin{cases}\frac{1}{1+\text{e}^{\frac{1}{\text{x}}}},&\text{x}\neq0\\0,&\text{x}=0\end{cases}$ then f(x) is:
  1. Continuous as well as differentiable at x = 0
  2. Continuous but not differentiable at x = 0
  3. Differentiable but not continuous at x = 0
  4. None of these.
$\big(\vec{\text{a}}+\vec{\text{b}}\big).\big(\vec{\text{b}}+\vec{\text{c}}\big)\times\big(\vec{\text{a}}+\vec{\text{b}}+\vec{\text{c}}\big)=$
  1. $0$
  2. $-\big[\vec{\text{a}}\vec{\text{b}}\vec{\text{c}}\big]$
  3. $2\big[\vec{\text{a}}\vec{\text{b}}\vec{\text{c}}\big]$
  4. $\big[\vec{\text{a}}\vec{\text{b}}\vec{\text{c}}\big]$
The objective function of an LPP is
Choose the correct answer from the given four option.
The degree of the differential equation $\Big[1+\Big(\frac{\text{d}\text{y}}{\text{d}\text{x}}\Big)^2\Big]^{\frac{3}{2}}=\frac{\text{d}^2\text{y}}{\text{d}\text{x}^2}$ is:
  1. 4
  2. $\frac{3}{2}$
  3. Not defined
  4. 2
Write the number of points where f(x) = |x + 2| + |x - 3| is not differentiable:
  1. 2
  2. 0
  3. 1
  4. 3
If $\left| {\,\begin{array}{*{20}{c}}a&b&c\\m&n&p\\x&y&z\end{array}\,} \right| = k$, then $\left| {\,\begin{array}{*{20}{c}}{6a}&{2b}&{2c}\\{3m}&n&p\\{3x}&y&z\end{array}\,} \right| = $
Choose the correct answer from the given four options.

A bag contains 5 red and 3 blue balls. If 3 balls are drawn at random without replacement the probability of getting exactly one red ball is:

  1. $\frac{45}{196}$

  2. $\frac{135}{392}$

  3. $\frac{15}{56}$

  4. $\frac{15}{29}$