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TS EAMCET · Maths · Definite Integration

\(\int_0^\pi \frac{\theta \sin \theta}{1+\cos ^2 \theta} d \theta\) is equal to

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

Answer & Solution

Correct Answer

(D) \(\frac{\pi^2}{4}\)

Step-by-step Solution

Detailed explanation

Let \(I=\int_0^\pi \frac{\theta \sin \theta}{1+\cos ^2 \theta} d \theta\) ...(i) \(=\int_0^\pi \frac{(\pi-\theta) \sin (\pi-\theta)}{1+\cos ^2(\pi-\theta)} d \theta\)\(\Rightarrow \quad I=\int_0^\pi \frac{(\pi-\theta) \sin \theta}{1+\cos ^2 \theta} d \theta\) ...(ii) On adding…