| | Encyclopedia :: encyclopedia : Ruler-and-compass construction (Site not responding. Last check: 2007-11-01) |
 | | The ruler is infinitely long, but it has no markings on it and has only one edge (thus making it a straightedge instead of what we usually think of as a ruler). |
 | | Without the constraint of requiring solution by ruler and compass alone, the problem is easily solvable by a wide variety of geometric and algebraic means, and has been solved many times in antiquity. |
 | | It is impossible to take a square root with just a ruler, so some things cannot be constructed with a ruler that can be constructed with a compass; but (by the Poncelet-Steiner theorem) given a single circle and its center, they can be constructed. |
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