"Annotated" dissection of Golden (or any) Rectangle to square: gosper.org/gold2square.gif Seven of the "swimming triangle" dissections (two very similar) of the half-rectangle to half-square: gosper.org/gold2halfsquare.gif Each triplet demonstrates the area formula A = ½bh for the intermediate (non-right) △ for two different choices of (b,h). (The middle school "proof" via a half-parallelogram fails if it's too skew to dissect into a rectangle in one cut.) --rwg Oops! Target #2 isn't Right! Ignore that one for now. If you're adventuresome, the notebook that made these, gosper.org/easyarea.nb was saved while running a ListAnimate of gold2halfsquare. If I load this nb and fail to pause the ListAnimate (near the end), it crashes Mathematica in a minute or two!