| 释义 |
bitangent Geom.|baɪˈtændʒənt|
[bi-2. Cf. F. bitangente.]
A line that touches a curve or surface at two different points; a double tangent. Hence bitanˈgential a., designating a curve that passes through the points of contact of the bitangents of a given curve; also ellipt.
1873G. Salmon Treat. Higher Plane Curves (ed. 2) vi. 218 Through the four points of contact of any two bitangents we can describe five conics. Ibid. ix. 336 The equation of the bitangential curve of a quartic. Ibid. 340 If the equation of this tangential curve were once formed, then, by forming the condition that the given tangent should touch this curve, we should immediately have the equation of the bitangential. 1948J. W. Archbold Introd. Algebr. Geom. Plane vii. 271 The only ‘multiple lines’ of the tangent envelope C are β bitangents of C and the tangents at ι simple inflexions. |