❤️Math Follow Me and Practice everyday 💯
🤔️跟我一起做💯
🌹Topic today：
🔑Key words：Length of the Curve，Arc Length用定积分求曲线弧长
▶️ derivative导数，continuous连续，interval区间
▶️ curve defined parametrically by the equation用参数方程定义的曲线
▶️position位置，distance the particle travels粒子运动的距离
