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WBJEE · Maths · Definite Integration

If \(f(x)=\int_0^{\sin ^2 x} \sin ^{-1} \sqrt{t}\) \(dt\) and \(g(x)=\int_0^{\cos ^2 x} \cos ^{-1} \sqrt{t}\) \(dt\), then the value of \(f(x)+g(x)\) is

  1. A \(\pi\)
  2. B \(\frac{\pi}{4}\)
  3. C \(\frac{\pi}{2}\)
  4. D \(\sin ^2 x+\sin x+x\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{\pi}{4}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} \text f^{\prime}(x)+g^{\prime}(x)=0 \\ & \Rightarrow f(x)+g(x)=\text { constant }(\text { say } c) \\ & \text { putting } x=\frac{\pi}{4} \\ \therefore & c=\int_0^{1 / 2}\left(\sin ^{-1} \sqrt{t}+\cos ^{-1} \sqrt{t}\right) d t=\frac{\pi}{4}\end{aligned}\)