Given two curves and and a fixed point , let a line from cut at and at . Then the locus of a point such that is the cissoid. The word cissoid means "ivy shaped."

curve 1	curve 2	pole	cissoid
line	parallel line	any point	line
line	circle	center of circle	conchoid of Nicomedes
circle	circle tangent line	on circumference	oblique cissoid
circle	circle tangent line	on circumference opposite tangent	cissoid of Diocles
circle	radial line	on circumference	strophoid
circle	concentric circle	center of circles	circle
circle	same circle		lemniscate

Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 53-56 and 205, 1972.

Lockwood, E. H. "Cissoids." Ch. 15 in A Book of Curves. Cambridge, England: Cambridge University Press, pp. 130-133, 1967.

Yates, R. C. "Cissoid." A Handbook on Curves and Their Properties. Ann Arbor, MI: J. W. Edwards, pp. 26-30, 1952.

CITE THIS AS:

Weisstein, Eric W. "Cissoid." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/Cissoid.html