One triangle is isometric to another triangle if it has the same size and shape. This means that it must have the same angles and side lengths as the other triangle.
Applying an isometric transformation to a triangle produces a new triangle that is isometric to the first. The isometric transformations are translation, which moves the triangle to a new position in the graph, reflection, which flips the triangle across a line, and rotation, which turns the triangle around the origin of the graph. A triangle that is produced by one of these transformations retains the size and shape of the original.
Isometrics involves using force on an immovable object, such as a wall. The muscle develops tension without changing length. Holding your muscle in a fixed position with no movement
http://www.ehow.com/how_5731066_isometricsmuscle...

isometric just means same measure. I have never heard this term used this way, but I suppose the isometric triangle would be the regular or equilateral triangle. For a quadrilateral
http://answers.yahoo.com/question/index?qid=200706...

A sketch that is equal on both sides.
http://wiki.answers.com/Q/What_is_isometric_sketch

( ¦ī·sə′me·trik kən′trak·shən ) (physiology) A contraction in which muscle tension is increased, but the muscle is not
http://www.answers.com/topic/isometriccontraction
