Polyiamond

A polyiamond (also polyamond or simply iamond) is a polyform whose base form is an equilateral triangle. The word polyiamond is a back-formation from diamond, because this word is often used to describe the shape of a pair of equilateral triangles placed base to base, and the initial `di-` looked like a Greek prefix meaning `two-`. ==Counting=...
Found on http://en.wikipedia.org/wiki/Polyiamond

polyiamond

A shape made from identical equilateral triangles that have been joined at their edges. See also polyomino.
Found on http://www.daviddarling.info/encyclopedia/P/polyiamond.html
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