(1)画图可知m最小值为π(19/8-17/8)=π/4
(2)同样画图可知p∈(0,3)∪(3,2+根号2)
p∈(0,3)时,x1+x2=3π/4;
p∈(3,2+根号2)时,x1+x2=7π/4.