| 摘要 |
The invention refers to a teaching device for visualising geometric loci in planar geometry, used as a teaching aid in education. According to the invention, the teaching device includes a frame (3) which rests on two holders (4) and a plate (2) on which a sheet (1) is superimposed; the sheet includes a sector (A) for the visualisation of the mid-perpendicular, a sector (B) for the visualisation of the geometric locus of the points situated at an equal distance to a straight line, a sector (C) for the visualisation of the bisector, a sector (D) for the visualisation of a circle, a sector (E) for the visualisation of the geometric locus of all the points from which a segment is seen under a given angle, a sector (F) for the visualisation of geometric loci as concentric circles, a sector (G) for the visualisation of an ellipse, a sector (H) for the visualisation of a hyperbole, and a sector (J) for the visualisation of a parable, in this respect using straight (5, 25) or curved lines (21, 26, 33, 34, 39 and 44), drawn on sheet (1), fixed bars (13, 14, 16, 17 and 46), on which mobile bars (11, 19, 20 and 48) can slide, hinged bars (7, 8, 27, 28 and 42) which are in permanent contact with an end executed from a permanent magnet of cursors (K, L, M, N, P, R and S) which move along some slits (b, d, f, h, m, p and r), a lever (23) driven by a crank (22), rings (29 and 31) on which a transparent disk (32) rolls and some textile strings (37, 43 and 49) which keep the cursors at a given distance from some fixed points (35, 36, 40, 41 and 45).
|
