x = tanθ
\int_{0}^{\pi /4}{\frac{2+tan^{2} \theta}{(1+tan^{2} \theta)^{3}}sec^{2} \theta d \theta}
\int_{0}^{\pi /4}{(cos^{4} \theta + cos^{2} \theta) d \theta}
x = tanθ
\int_{0}^{\pi /4}{\frac{2+tan^{2} \theta}{(1+tan^{2} \theta)^{3}}sec^{2} \theta d \theta}
\int_{0}^{\pi /4}{(cos^{4} \theta + cos^{2} \theta) d \theta}