I=∫6π4πsin2x(tan5x+cot5x)dx $\begin{array}{l}
=\int_{\frac{\pi}{6}}^{\frac{\pi}{4}} \frac{\tan ^{5} x \cdot \sec ^{2} x}{2 \frac{\sin x}{\cos x}\left(\left(\tan ^{5} x\right)^{2}+1\right)} \
=\frac{1}{2} \int_{\frac{\pi}{6}}^{\frac{\pi}{4} \tan ^{4} x \cdot \sec ^{2} x}{\left(\tan ^{5} x\right)^{2}+1} d x
\end{array}Let\tan ^{4} x=t5 \tan ^{4} x \cdot \sec ^{2} x d x=d tWhenx \rightarrow \frac{\pi}{4}thent \rightarrow 1andx \rightarrow \frac{\pi}{6}thent \rightarrow\left(\frac{1}{\sqrt{3}}\right)^{5}\begin{aligned}
\therefore \quad & \mathrm{I}=\frac{1}{10} \int_{\left(\frac{1}{\sqrt{3}}\right)^{5}}^{1} \frac{d t}{t^{2}+1} \
&=\frac{1}{10}\left(\frac{\pi}{4}-\tan ^{-1}\left(\frac{1}{9 \sqrt{3}}\right)\right)
\end{aligned}$