主题
Search

Ceva 摆线


CycloidofCeva

极坐标曲线

 r=1+2cos(2theta)
(1)

可以用于角的三等分。它由 Ceva 于 1699 年设计,他称之为 cycloidum anomalarum (Loomis 1968, p. 29)。它具有笛卡尔方程

 (x^2+y^2)^3=(3x^2-y^2)^2.
(2)

它具有面积

 A=3pia^2
(3)

弧长

s=a[16E(k)-3K(k)+3Pi(1/4,k)]
(4)
=20.01578...a
(5)

(OEIS A138497), 其中 k=sqrt(13)/4, 其中 K(k), E(k), 并且 Pi(z,k) 分别是第一类第二类第三类完全椭圆积分

弧长函数是一个稍微复杂的表达式,可以用椭圆函数的闭合形式表示,曲率由下式给出

 kappa(t)=(3[9+4cos(2t)-2cos(4t)])/([11+4cos(2t)-6cos(4t)]^(3/2)).
(6)

另请参阅

角的三等分, 摆线, 三等分角曲线

使用 Wolfram|Alpha 探索

参考文献

Loomis, E. S. "The Cycloid of Ceva." §2.7 in The Pythagorean Proposition: Its Demonstrations Analyzed and Classified and Bibliography of Sources for Data of the Four Kinds of "Proofs," 2nd ed. Reston, VA: National Council of Teachers of Mathematics, pp. 29-30, 1968.Loy, J. "Trisection of an Angle." http://www.jimloy.com/geometry/trisect.htm#curves.Sloane, N. J. A. Sequence A138497 in "The On-Line Encyclopedia of Integer Sequences."Yates, R. C. The Trisection Problem. Reston, VA: National Council of Teachers of Mathematics, 1971.

请将此页引用为

Weisstein, Eric W. "Cycloid of Ceva." 来自 MathWorld--Wolfram Web 资源. https://mathworld.net.cn/CycloidofCeva.html

主题分类