在正方形內旋轉時，始終與四邊保持接觸的曲線。這類曲線有時也稱為滾子。
封閉凸曲線的“寬度”定義為包圍它的平行線（“支撐線”）之間的距離。每個定寬曲線都是凸的。定寬曲線無論在平行線之間的方向如何，都具有相同的“寬度”。實際上，它們也具有相同的周長（巴比耶定理）。例子包括圓（具有最大面積）和勒洛三角形（具有最小面積），但存在無數個。定寬曲線可以用於特殊的鑽夾頭來切割方形“孔”。
推廣得到定寬體。對於給定的寬度，它們不具有相同的表面積，但它們的陰影是具有相同寬度的定寬曲線！
定寬曲線
另請參閱
Delta 曲線, Kakeya 針問題, 勒洛三角形, 定寬體使用 探索
參考文獻
Blaschke, W. "Konvexe Bereiche gegebener konstanter Breite und kleinsten Inhalts." Math. Ann. 76, 504-513, 1915.Bogomolny, A. "Shapes of Constant Width." http://www.cut-the-knot.org/do_you_know/cwidth.shtml.Bogomolny, A. "Star Construction of Shapes of Constant Width." http://www.cut-the-knot.org/Curriculum/Geometry/CWStar.shtml.Böhm, J. "Convex Bodies of Constant Width." Ch. 4 in Mathematical Models from the Collections of Universities and Museums (Ed. G. Fischer). Braunschweig, Germany: Vieweg, pp. 96-100, 1986.Croft, H. T.; Falconer, K. J.; and Guy, R. K. Unsolved Problems in Geometry. New York: Springer-Verlag, p. 7, 1991.Fischer, G. (Ed.). Plates 98-102 in Mathematische Modelle aus den Sammlungen von Universitäten und Museen, Bildband. Braunschweig, Germany: Vieweg, pp. 89 and 96, 1986.Gardner, M. "Mathematical Games: Curves of Constant Width, One of which Makes it Possible to Drill Square Holes." Sci. Amer. 208, 148-156, Feb. 1963.Gardner, M. "Curves of Constant Width." Ch. 18 in The Unexpected Hanging and Other Mathematical Diversions. Chicago, IL: Chicago University Press, pp. 212-221, 1991.Goldberg, M. "Circular-Arc Rotors in Regular Polygons." Amer. Math. Monthly 55, 393-402, 1948.Kelly, P. Convex Figures. New York: Harcourt Brace, 1995.Rademacher, H. and Toeplitz, O. The Enjoyment of Mathematics: Selections from Mathematics for the Amateur. Princeton, NJ: Princeton University Press, 1957.Steinhaus, H. Mathematical Snapshots, 3rd ed. New York: Dover, pp. 150-151, 1999.Wells, D. The Penguin Dictionary of Curious and Interesting Geometry. London: Penguin, pp. 219-220, 1991.Yaglom, I. M. and Boltyanski, V. G. Convex Figures. New York: Holt, Rinehart, and Winston, 1961.在 中被引用
定寬曲線請引用為
Weisstein, Eric W. "定寬曲線。" 來自 Web 資源。 https://mathworld.tw/CurveofConstantWidth.html