\(\\\\ \int \frac{tg^{3}x}{secx}dx \\\\ \int \frac{\frac{sen^{3}x}{cos^{3}x}}{\frac{1}{cosx}}dx \\\\ \int \frac{sen^{3}x}{cos^{2}x}dx \\\\ \int \frac{senx*sen^{2}x}{cos^{2}x}dx \\\\ \int \frac{senx*(1-cos^{2}x)}{cos^{2}x}dx\)
agora utilizaremos a substituição \(u=cosx\) , \(du=-senx dx\) :
\(\\\\ -\int \frac{1-u^{2}}{u^{2}}du \\\\ -\int \frac{1}{u^{2}}du+\int \frac{u^{2}}{u^{2}}du \\\\ -(-\frac{1}{u})+u+C \\\\ \frac{1}{cosx}+cosx+C\)
Por favor confira com o gabarito e confira minhas contas tbm.
att mais