Verified Solution • 2025–26 Session moderate

QJEEM19Maba4e: JEE Main 2019 Mathematics - Class 12 JEEM19Maba4e Solution

lim⁡x→1−π−2sin⁡−1x1−x\mathop {\lim }\limits_{x \to {1^ - }} {{\sqrt \pi - \sqrt {2{{\sin }^{ - 1}}x} } \over {\sqrt {1 - x} }} is equal to :

Multiple Choice Options

  • A 2π\sqrt {{2 \over \pi }}
  • B 12π{1 \over {\sqrt {2\pi } }}
  • C π2\sqrt {{\pi \over 2}}
  • D π\sqrt \pi

Step-by-Step Verified Solution

lim⁡x→1−π−2sin⁡−1x1−x×π+2sin⁡−1π+2sin⁡−1x\mathop {\lim }\limits_{x \to {1^ - }} {{\sqrt \pi - \sqrt {2{{\sin }^{ - 1}}x} } \over {\sqrt {1 - x} }} \times {{\sqrt \pi + \sqrt {2{{\sin }^{ - 1}}} } \over {\sqrt \pi + \sqrt {2{{\sin }^{ - 1}}x} }}

lim⁡x→1−2(π2−sin⁡−1x)1−x(π+2sin⁡−1x)\mathop {\lim }\limits_{x \to {1^ - }} {{2\left( {{\pi \over 2} - {{\sin }^{ - 1}}x} \right)} \over {\sqrt {1 - x} \left( {\sqrt \pi + \sqrt {2{{\sin }^{ - 1}}x} } \right)}}

lim⁡x→1−2cos⁡−1x1−x.12π\mathop {\lim }\limits_{x \to {1^ - }} {{2{{\cos }^{ - 1}}x} \over {\sqrt {1 - x} }}.{1 \over {2\sqrt \pi }}

Put   x=cos⁡θx = \cos \theta

lim⁡x→0+2θ2sin⁡(θ2).12π\mathop {\lim }\limits_{x \to {0^ + }} {{2\theta } \over {\sqrt 2 \sin \left( {{\theta \over 2}} \right)}}.{1 \over {2\sqrt \pi }}

=2π= \sqrt {{2 \over \pi }}

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