‍在欠阻尼状态下，ξ<1。写出有阻尼自由振动的周期<img src="https://static.zxtiku.com/wangke/imgs/topic/68a522148904ea04772455e269b6095a.png"/>和角频率<img src="https://static.zxtiku.com/wangke/imgs/topic/d7182faa101761dc33a151df60d234df.png"/>与相应的无阻尼自由振动的T、f 和<img src="https://static.zxtiku.com/wangke/imgs/topic/82668792b455dd3655df2526ffab0a7e.png"/>的关系_______________。‏