Machine-translated by Google. Questions are authored in English.
Top

Discussion

\(\displaystyle \int (\cot 2x + \mathrm{cosec}\, 2x)\,dx =\)

  • A.\(2\log_{e}|\sin x| + C\)
  • B.\(\frac{1}{2}\log_{e}|\sin x| + C\)
  • C.\(\log_{e}|\cos x| + C\)
  • D.\(2\log_{e}|\cos x| + C\)
  • E.\(\log_{e}|\sin x| + C\)

Answer: E

The integral is \(\log_{e}|\sin x| + C\).

Combine the two terms with the double-angle formulas:

\[ \begin{aligned} \cot 2x + \mathrm{cosec}\,2x &= \frac{\cos 2x + 1}{\sin 2x} \\ &= \frac{2\cos^{2}x}{2\sin x\cos x} = \cot x \end{aligned} \]

\[ \int \cot x\,dx = \log_{e}|\sin x| + C \]

Integrating each term separately and then forgetting to simplify can suggest a factor of \(\frac{1}{2}\) or 2, but the combined integrand is exactly \(\cot x\).

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.