设平面曲线<img src="https://static.zxtiku.com/wangke/imgs/topic/4dc1b766d887ab22c77cf4e7c320d499.png"/>，则其弧长计算公式为‌<br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/303c8b05a27b93c43a772d6501651817.png"/>．‌