Verified Solution • 2025–26 Session moderate

QJEEM04Ma74f6: JEE Main 2004 Mathematics - Class 12 JEEM04Ma74f6 Solution

∫dxcos⁡x−sin⁡x\int {{{dx} \over {\cos x - \sin x}}} is equal to

Multiple Choice Options

  • A 12log⁡∣tan⁡(x2+3π8)∣+C{1 \over {\sqrt 2 }}\log \left| {\tan \left( {{x \over 2} + {{3\pi } \over 8}} \right)} \right| + C
  • B 12log⁡∣cot⁡(x2)∣+C{1 \over {\sqrt 2 }}\log \left| {\cot \left( {{x \over 2}} \right)} \right| + C
  • C 12log⁡∣tan⁡(x2−3π8)∣+C{1 \over {\sqrt 2 }}\log \left| {\tan \left( {{x \over 2} - {{3\pi } \over 8}} \right)} \right| + C
  • D  12log⁡∣tan⁡(x2−π8)∣+C\,{1 \over {\sqrt 2 }}\log \left| {\tan \left( {{x \over 2} - {\pi \over 8}} \right)} \right| + C

Step-by-Step Verified Solution

∫dxcos⁡x−sin⁡x\int {{{dx} \over {\cos x - \sin x}}}

=∫dx2cos⁡(x+π4)= \int {{{dx} \over {\sqrt 2 \cos \left( {x + {\pi \over 4}} \right)}}}

=12∫sec⁡(x+π4)dx= {1 \over {\sqrt 2 }}\int {\sec \left( {x + {\pi \over 4}} \right)dx}

=12log⁡∣tan⁡(π4+x2+π8)∣+C= {1 \over {\sqrt 2 }}\log \left| {\tan \left( {{\pi \over 4} + {x \over 2} + {\pi \over 8}} \right)} \right| + C

[ \left[ \, \right. As ∫sec⁡x dx=log⁡∣tan⁡(π4+x2)∣\int {\sec x\,dx} = \log \left| {\tan \left( {{\pi \over 4} + {x \over 2}} \right)} \right|  ]\left. \, \right]

=12log⁡∣tan⁡(x2+3π8)∣+C= {1 \over {\sqrt 2 }}\log \left| {\tan \left( {{x \over 2} + {{3\pi } \over 8}} \right)} \right| + C

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