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AP EAMCET · Maths · Indefinite Integration

Find the value of \(k\) if \(\int \cos ^k(x) \sin (x) d x=\frac{-1}{4}\) \(\cos ^4(x)+c\)

  1. A \(4\)
  2. B \(3\)
  3. C \(2\)
  4. D \(1\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(3\)

Step-by-step Solution

Detailed explanation

To find \(k\) Given, \(\int \cos ^k(x) \sin (x) d x=\frac{-1}{4} \cos ^4(x)+C\) Let \(I=\int \cos ^k(x) \sin (x) d x\) Let \(\cos x=t\) \(\Rightarrow \quad-\sin x d x=d t\) \(\sin x d x=-d t\) \(\therefore \quad I=-\int t^k d t\)…