\(\int\dfrac{1}{1+sinx}dx=\int\dfrac{1-sinx}{\left(1-sinx\right)\left(1+sinx\right)}dx=\int\dfrac{1-sinx}{1-sin^2x}dx\)
\(=\int\dfrac{1-sinx}{cos^2x}dx=\int\dfrac{dx}{cos^2x}+\int\dfrac{-sinx.dx}{cos^2x}=\int\dfrac{dx}{cos^2x}+\int\dfrac{d\left(cosx\right)}{cos^2x}\)
\(=tanx-\dfrac{1}{cosx}+C\)