Kaynine said, "An exercise in using frame-by-frame animation alongside tweening to synchronise movement with music.
And just in case you are wondering why the triangle features in a movie with the title 'Trapezium tango', here's the explanation ....
Triangles are sensual, subversive things; always rubbing themselves up against quadrilaterals and other shapes, yet known for their own inner strength and sense of balance. Nevertheless, they tend towards loneliness and jealousy and forever want to be joined to other shapes in various dubious ways because (although no triangle will ever admit this), they have never recovered from the discovery that they can be seen as the long-lost fragment of a mythical trapezium which, in ages past, transformed itself into an irregular quadrilateral.
In my little movie, the triangle is attempting to return to a state of integrated bliss with the rectangle, but the isosceles trapezium is standoff-ish until its own suppressed emotions are aroused when it sees the triangle (also isosceles) trying to mate with the quadrilateral. All that follows is, of course, a mathematical dance until, right at the end, the triangle pierces both the rectangle and the trapezium and leads them off to a life of very UNmathematical debauchery"