conchoid
/ˈkɒŋkɔɪd/noun
1- Mathematics a plane quartic curve consisting of two separate branches either side of and asymptotic to a central straight line (the asymptote), such that if a line is drawn from a fixed point (the pole) to intersect both branches, the part of the line falling between the two branches is of constant length and is exactly bisected by the asymptote【数】蚌线。
1.1
- Such curves are represented by the general equation (x - a)2(x2+y2) = b2x2, where a is the distance between the pole and the asymptote, and b is the constant length. The branch on the same side of the asymptote as the pole typically has a cusp or loop蚌线由等式(x-a)2(x2+y2)=b2x2表示, 其中a是坐标极点与渐近线间的距离, b是恒长。渐近线这边的曲线支有一尖点或圈。
词源
early 18th cent.: from CONCH+-OID.