xcosx/(1+sinx^2)这项也是奇函数,所以是0只剩下cosx/(1+sinx^2)了积分(-π/2到π/2) [ cosx/(1+sinx^2) ]dx=积分(-π/2到π/2) [ 1/(1+sinx^2) ]dsinx=arctan(sinx) | (-π/2到π/2)=2arctan1=π/2...