Question

判断下列级数的收敛性,并写出判断过程

Answer 1

2sin(π/12)*sin(nπ/6)=cos{(2n-1)π/12}-cos{(2n+1)π/12}

所以 Sn={1/2sin(π/12)}*{cos(π/12)-cos(2n+1)π/12} cos(2n+1)π/12的极限不存在

所以 发散