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MHT CET · Maths · Definite Integration

\(\int_0^{\pi / 4} \sqrt{1-\sin 2 x} d x=\)

  1. A \(\sqrt{2}+1\)
  2. B \(1+2 \sqrt{2}\)
  3. C \(\sqrt{2}-1\)
  4. D \(2 \sqrt{2}-1\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\sqrt{2}-1\)

Step-by-step Solution

Detailed explanation

\(\int_0^{\pi / 4} \sqrt{1-\sin 2 x} \mathrm{~d} x=\int_0^{\pi / 4}\) \(\sqrt{\cos ^2 x+\sin ^2 x-2 \sin x \cdot \cos x} \mathrm{~d} x \)
\( =\int_0^{\pi / 4} \sqrt{(\cos x-\sin x)^2} \mathrm{~d} x=\int_0^{\pi / 4}|\cos x-\sin x| \mathrm{d} x \)
\( =\int_0^{\pi / 4}(\cos x-\sin x) \mathrm{d} x=[\sin x+\cos x]_0^{\pi / 4} \)
\( =\left(\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{2}}\right)-(0+1)=-1\)