The larger an arc is, the smaller its radius appears. For example, the three arcs illustrated above belong circles of the same radius.

*This entry contributed by Margherita Barile*

REFERENCES:

Carraher, R. G. and Thurston, J. B. *Optical Illusions and the Visual Arts.* New York: Reinhold, 1966.

CITE THIS AS:

Barile, Margherita. "Three-Arc Illusion." From *MathWorld*–A Wolfram Web Resource, created by Eric W. Weisstein. http://mathworld.wolfram.com/Three-ArcIllusion.html