Solve this :

$$\begin{gathered} 16. \int \frac{1}{{\sin }^2 {\mathrm{xcos}}^2 \mathrm{x}}\mathrm{dx} \\ 17. \int {\sin }^2 \left(2\mathrm{x}+5\right)\mathrm{dx} \\ 18. \int \sin 3\mathrm{x} \cos 4\mathrm{x} \mathrm{dx} \\ 19. \int \cos 2\mathrm{x} \cos 4\mathrm{x} \cos 6\mathrm{x} \mathrm{dx} \end{gathered}$$

Please find below the link of similar query as asked by you :

16 ) https://www.meritnation.com/ask-answer/question/1-sin2xcos2x/integrals/8450435

17 ) https://www.meritnation.com/ask-answer/question/how-to-integrate-sin2-2x-5-and-sin4xcos2xx/integrals/9197837

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