sinX /(1+X^2) 为奇函数,在对称区间积分为0
∫{ [sinX /(1+X^2) ]+(sinX)^2}dX
=∫(sinX)^2dX
=0.5∫(1-cos 2x)dx
=0.5(x-0.5sin2x)
=∏/2