Length of an arc, the Huygens formula

length arc Huygens formula

M14 red  -  chord   AB

m12 blue  -  chord  AD=DB

The point C divides the segment AB in half

The angles ACD and DCB are right angles (90°)

 

Calculate the Length of an arc by the Huygens formula ( L  ) :

length arc Huygens formula F

*Accuracy for the angles less than 60° is less than 0.5%