Constructible number
- 规矩数（规矩数是可用尺规作图方式作出的实数，表示可用圆规及直尺作图的重要元素。若给定单位长度，可用尺规作图方式作出长度为a的线段，则a为规矩数）
Constructible number
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abstract:
A point in the Euclidean plane is a constructible point if, given a fixed coordinate system (or a fixed line segment of unit length), the point can be constructed with unruled straightedge and compass. A complex number is a constructible number if its corresponding point in the Euclidean plane is constructible from the usual x- and y-coordinate axes.
以上来源于:
WordNet