令x-1=sint,-π小于t小于π.
原始=2∫(sint+1)cost.costdt ,上下限先不写,不方便写
=-2∫cost.costdcost+∫cos2t+1dt
=(-2cost.cost.cost/3+sin2t/2+t)上下限为正负π,代入
=2π
令x-1=sint,-π小于t小于π.
原始=2∫(sint+1)cost.costdt ,上下限先不写,不方便写
=-2∫cost.costdcost+∫cos2t+1dt
=(-2cost.cost.cost/3+sin2t/2+t)上下限为正负π,代入
=2π