∫02π[2sinx]dx=
−5π3
−π
5π3
−2π
I=∫0π60.dx+∫π65π61.dx+∫5π6π0.dx+∫π7π6(−1)dx+∫7π611π6(−2)dx+∫11π62π(−1)dx
=4π6−π6−8π6−π6=−π