Given
∫12π4π(tanx+cotx)38cos2xdx=∫12π4π(cosxsinx+sinxcosx)38cos2xdx
=∫12π4π(sin2x1)3cos2x=∫12π4πcos2x⋅sin2x⋅sin2(2x)dx
=41∫12π4πsin4x⋅(1−cos4x)dx
=41∫12π4πsin4x−81∫12π4πsin8x
=−161[cos4x]12π4π+8×81[cos8x]12π4π
=−161[−1−21]+641[1+21]
=12815.