The calculation formula of arc length is a mathematical formula, L=n× π× r/ 180, L = α× r ... where N is the degree of central angle (angular system), R is the radius, L is the arc length of central angle, and α is the extended data of central angle (arc system). Note: ds and dx, dy are pythagorean relations: dx and dy are two right-angled sides, and ds is the differential of arc. The micro-arc is regarded as a straight line segment.

Therefore, ds = √ (dx+dy); Then divide the two terms in the root sign by dt, and then multiply them by dt outside the root sign, that is, do not multiply or divide, male.

That's how the formula came about.

Arc length formula:

L = n (central angle) ×π(π)× r (radius)/180=α (radian of central angle )× r (radius)

In a circle with radius r, because the arc length subtended by the central angle 360 is equal to the circumference C=2πr, the arc length subtended by the central angle n is L = n π r ÷ 180 (L = n X2π r/360).