斜率直观入门与探索

斜率直观入门与探索
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2017-03-09 04:24
本GeoGebra范例旨在直观演示直线斜率的概念及其动态变化。它通过一个可交互的图示,展示当直线上的点移动时,斜率如何相应调整。涉及的核心数学概念包括斜率的几何意义、直线方程的斜截式、以及坐标几何中的比率计算。在作图方面,构造摘要显示使用了多种GeoGebra命令,如GCD(用于简化分数)、If(条件判断)、OrthogonalLine(正交线)、Intersect(交点)、Line(直线)、Polygon(多边形)、Distance(距离)、Segment(线段)、Angle(角度)、Slope(斜率)、Dilate(缩放)、Vector(向量)、Midpoint(中点)、Mirror(镜像)等,以及关键对象如A、B、deltaY、deltaX、numerYint等,这些共同构建了一个动态模型,允许用户调整点并观察斜率的实时变化。此范例适合中学数学教学,特别是引入斜率概念时,能帮助学生理解斜率与直线倾斜程度的关系。

GeoGebra 命令及参数

  1. GCD(deltaY, deltaX) → GCDm
  2. GCD(numerYint, deltaX) → GCDy
  3. If(sgn(deltaY / deltaX) ≥ 0, "", "-") → textSignN
  4. If(sgn(numerYint / deltaX) > 0, "+", "-") → textSign
  5. If(deltaXR ≟ 1, textSignN + deltaYR, textSignN + "\, \frac{" + deltaYR + "}{" + deltaXR + "}") → textslopeN
  6. If(denomYintR ≟ 1, textSign + numerYintR, textSign + "\frac{" + numerYintR + "}{" + denomYintR + "}") → textYint
  7. If(denomYintR ≟ 1, If[numerYintR ≟ 1, textSign, textSign + numerYintR], textSign + "\frac{" + numerYintR + "}{" + denomYintR + "}") → textMID
  8. OrthogonalLine(B, xAxis) → a_2
  9. OrthogonalLine(A, yAxis) → c
  10. Intersect(a_2, c) → C
  11. Line(A, B) → d
  12. Polygon(A, B, C) → poly1, c_1, a_1, b_1
  13. Distance(B, C) → distanceBC
  14. Distance(A, C) → distanceAC
  15. Intersect(a_2, c) → D
  16. Segment(A, D) → e
  17. Segment(C, B) → f
  18. GCD(deltaY_1, deltaX_1) → GCDm_1
  19. If(sgn(deltaY_1 / deltaX_1) ≥ 0, "", "-") → textSignN_1
  20. If(deltaXR_1 ≟ 1, textSignN_1 + deltaYR_1, textSignN_1 + "\, \frac{" + deltaYR_1 + "}{" + deltaXR_1 + "}") → textslopeN_1
  21. Line(A_1, B_1) → d_1
  22. Angle(B, D, A) → α
  23. Segment(A, B) → g
  24. GCD(deltaY_2, deltaX_2) → GCDm_2
  25. If(sgn(deltaY_2 / deltaX_2) ≥ 0, "", "-") → textSignN_2
  26. If(deltaXR_2 ≟ 1, textSignN_2 + deltaYR_2, textSignN_2 + "\, \frac{" + deltaYR_2 + "}{" + deltaXR_2 + "}") → textslopeN_2
  27. Line(A_2, B_2) → d_2
  28. Segment(A_2, B_2) → g_1
  29. GCD(deltaY_3, deltaX_3) → GCDm_3
  30. If(sgn(deltaY_3 / deltaX_3) ≥ 0, "", "-") → textSignN_3
  31. If(deltaXR_3 ≟ 1, textSignN_3 + deltaYR_3, textSignN_3 + "\, \frac{" + deltaYR_3 + "}{" + deltaXR_3 + "}") → textslopeN_3
  32. Line(A_3, B_3) → d_3
  33. Segment(A_3, B_3) → g_2
  34. Slope(g) → h
  35. Dilate(A, If[0 < i ≤ 1, 1 - i, 0], D) → A'
  36. Vector(A, A') → u
  37. Dilate(D, If[1 < i ≤ 2, 2 - i, 0], B) → D'
  38. Vector(D, D') → v
  39. Line(A, B) → j
  40. Midpoint(A, C) → E
  41. Mirror(B, k) → B'
  42. Distance(A, B') → distanceAB'
  43. Distance(B', B) → distanceB'B
  44. Polygon(A, B', B) → t1, b_5, a_6, b'
  45. Dilate(A, If[0 < i ≤ 1, 1 - i, 0], B') → A'_1
  46. Vector(A, A'_1) → w
  47. Dilate(B', If[1 < i ≤ 2, 2 - i, 0], B) → B''
  48. Vector(B', B'') → l
  49. Intersect(m, n) → F
  50. Dilate(A, If[0 < i ≤ 1, 1 - i, 0], F) → A'_2
  51. Vector(A, A'_2) → p
  52. Dilate(F, If[1 < i ≤ 2, 2 - i, 0], B) → F'
  53. Vector(F, F') → q
  54. Distance(A, F) → distanceAF
  55. Distance(F, B) → distanceFB
  56. Polygon(A, F, B) → t3, b_6, a_7, f_1