strophoid

American  

[strof-oid, stroh-foid] / ˈstrɒf ɔɪd, ˈstroʊ fɔɪd /

noun

Geometry.

1. a plane curve generated by the loci of points p and pprime; on a straight line that intersects the y-axis at a point n and the minus x-axis at a fixed point q, such that pn = npprime; = on, as on changes, where o is the origin. Equation: y 2 = x 2 (x +a )/(a −x ).

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strophoid Scientific  

/ strō′foid′ /

1. The curve traced out by points P and P ′ which lie on lines through a fixed point A where the midpoint M of PP ′ is on a fixed line and the absolute value ‖ PM ‖ equals the absolute value ‖ P ′ M ‖ equals the absolute value ‖ MO ‖, where O is the projection of A onto that fixed line.

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Etymology

Origin of strophoid

1875–80; < Greek stróph ( os ) twine + -oid, modeled on French strophoïde