L= pi*r*thetha/180

This formula represents the length of an arc on a circle, where:

- L is the length of the arc
- r is the radius of the circle
- theta is the angle subtended by the arc
- pi is a mathematical constant approximately equal to 3.14159

To calculate the length of an arc, you can multiply the radius of the circle by the angle in degrees and then by pi, finally dividing by 180.