Using the symmetry of integral domain to simplify integral calculation is one of the priority calculation strategies. If the integral domain is composed of two symmetrical parts,must examine whether the integral domain has directionality first,and then examine whether the value of integrand on the symmetrical points are equal or opposite.The integral twice times reduced to half an integral domain when the integral domain has no directionality and the value of integrand on the symmetrical points are equal.Th...