Paragraph: Given that for each $a \in(0,1)$, $\lim _{h \rightarrow 0^{+}} \int_{h}^{1-h} t^{-a}(1-t)^{a-1} d…

Paragraph: Given that for each $a \in(0,1)$, $\lim _{h \rightarrow 0^{+}} \int_{h}^{1-h} t^{-a}(1-t)^{a-1} d t$ exists. Let this limit be $g(a)$. In addition, it is given that the function $g(a)$ is differentiable on $(0,1)$. Question: The value of $g\left(\frac{1}{2}\right)$ is
  1. π
  2. 2π
  3. π2
  4. π4

Solution

g12=limh0+h1-ht-12 1-t-12 dt
=01dtt-t2=01dt14-t-122=sin-1t-121201
=sin-11-sin-1(-1)=π

Asked in: JEE Advanced 2014 (Paper 2)

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