parametre
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parametre
Parametre means often a quantity which is considered as constant in a certain situation but which may take different values in other situations; so the parametre is a “variable constant”. But in giving a curve or a surface in parametric form, the parametres work as proper variables which determine the values of the coordinates of the points; then we can describe the parametres as “auxiliary variables”.
of the origin-centered circle contains both above-mentioned sorts of parametres: (the radius) is a variable constant which is held constant all the time when one considers one circle; is an auxiliary variable which has to get all real values (e.g. from the interval ) for obtaining all points of the perimetre.
In the analytic geometry, one speaks of the parametre of parabola (a.k.a. latus rectum): it means the chord of the parabola which is perpendicular to the axis and goes through the focus; it is the quantity in the standard equation of the parabola ( is the distance of the focus and the directrix).
Mathematics Subject Classification
00A05 no label found
