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COMEDK · Maths · 30. Definite Integration

\(\int_\limits{-\dfrac{\pi}{2}}^{\dfrac{\pi}{2}} \sqrt{\cos x-\cos ^3 x} d x \text { is equal to }\)

  1. A 0
  2. B \(-\dfrac{2}{3}\)
  3. C \(-\dfrac{1}{3}\)
  4. D \(\dfrac{4}{3}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\dfrac{4}{3}\)

Step-by-step Solution

Detailed explanation

The integral is \(I = \int_{-\pi/2}^{\pi/2} \sqrt{\cos x - \cos^3 x} dx\). Since \(\cos x - \cos^3 x = \cos x(1 - \cos^2 x) = \cos x \sin^2 x\), the integrand becomes \(\sqrt{\cos x \sin^2 x} = |\sin x| \sqrt{\cos x}\). The integral is…