Geometric Art: Isolines, Triquetra, Celtic Knotwork, Trefoil Knot, Parallel Lines, Geometry for Kids, Software, iPad

Isoline
An isoline or contour line of a function of two variables is a curve along which the function has a constant value. Isolines usually have a parallel trend.

Parallel lines are lines in a plane which do not intersect or touch each other at any point.

Triquetra
Triquetra was used to refer to various three-cornered shapes. Topologically, the interlaced form of the plain triquetra is a trefoil knot. The triquetra is often used artistically as a design element when Celtic knotwork is used. Read more.