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QJEEM24Maeea7: JEE Main 2024 Mathematics - Class 12 JEEM24Maeea7 Solution: Let . If , then is equal to

Let I(x)=∫6sin⁡2x(1−cot⁡x)2dxI(x)=\int \frac{6}{\sin ^2 x(1-\cot x)^2} d x . If I(0)=3I(0)=3 , then I(π12)I\left(\frac{\pi}{12}\right) is equal to

Multiple Choice Options

  • A 3\sqrt3
  • B 232\sqrt3
  • C 636\sqrt3
  • D 333\sqrt3

Step-by-Step Verified Solution

amp;I(x)=∫6sin⁡2x(1−cot⁡x)2dxamp;I(x)=∫6(sin⁡x−cos⁡x)2dxamp;=∫6sec⁡2x(tan⁡x−1)2dx\begin{aligned}& I(x)=\int \frac{6}{\sin ^2 x(1-\cot x)^2} d x \\& I(x)=\int \frac{6}{(\sin x-\cos x)^2} d x \\& =\int \frac{6 \sec ^2 x}{(\tan x-1)^2} d x\end{aligned}

amp; Let tan⁡x=t⇒sec⁡2xdx=dtamp;=∫6dt(t−1)2amp;=−6(t−1)+camp;=−6(tan⁡x−1)+camp;I(x)=61−tan⁡x+camp;I(0)=3amp;61−tan⁡0+c=3amp;c=−3\begin{aligned}& \text { Let } \tan x=t \Rightarrow \sec ^2 x d x=d t \\& =\int \frac{6 d t}{(t-1)^2} \\& =-\frac{6}{(t-1)}+c \\& =\frac{-6}{(\tan x-1)}+c \\& I(x)=\frac{6}{1-\tan x}+c \\& I(0)=3 \\& \frac{6}{1-\tan 0}+c=3 \\& c=-3\end{aligned}

I(x)amp;=61−tan⁡x−3I(π12)amp;=61−tan⁡(π12)−3amp;=61−(2−3)−3amp;=63−1−3amp;=6−33+33−1amp;=9−333−1amp;=33(3−1)3−1amp;=33\begin{aligned}I(x) & =\frac{6}{1-\tan x}-3 \\I\left(\frac{\pi}{12}\right) & =\frac{6}{1-\tan \left(\frac{\pi}{12}\right)}-3 \\& =\frac{6}{1-(2-\sqrt{3})}-3 \\& =\frac{6}{\sqrt{3}-1}-3 \\& =\frac{6-3 \sqrt{3}+3}{\sqrt{3}-1} \\& =\frac{9-3 \sqrt{3}}{\sqrt{3}-1} \\& =\frac{3 \sqrt{3}(\sqrt{3}-1)}{\sqrt{3}-1} \\& =3 \sqrt{3}\end{aligned}

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