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MHT CET · Maths · Indefinite Integration

\(\int \frac{\sin 4 x}{\sin x} \mathrm{~d} x=\) (where \(C\) is a constant of integration.)

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

Answer & Solution

Correct Answer

(C) \(\frac{2 \sin 3 x}{3}+2 \sin x+C\)

Step-by-step Solution

Detailed explanation

\(\int \frac{\sin 4 x}{\sin x} \mathrm{~d} x=\int \frac{4 \sin x \cdot \cos x \cdot \cos 2 x}{\sin x} \mathrm{~d} x=2 \int 2\) \(\cos x \cdot \cos 2 x d x\)
\(=2 \int\{\cos 3 x+\cos x\} \mathrm{d} x\)
\(=2\left\{\frac{\sin 3 x}{3}+\sin x\right\}+c\)
\(=\frac{2}{3} \sin 3 x+2 \sin x+c\)