线积分:弧长与围栏面积
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①本范例演示通过线积分计算曲线的弧长及封闭区域的面积;②涉及核心数学概念包括线积分、定积分、圆的几何性质;③作图要点:使用 GeoGebra 命令 CurveCartesian 绘制曲线,Derivative 计算导数,Simplify 简化表达式,Integral 计算积分,Sum 求和,Textfield 添加文本说明,Sequence 创建序列;④适合高中及以上学生及微积分学习者,用于理解线积分在实际几何问题中的应用。
GeoGebra 命令及参数
CurveCartesian(pathx(i), pathy(i), pathz(i), i, ax, ay) → pathDerivative(path) → DpathSimplify(sqrt(x(Dpath(t))^(2) + y(Dpath(t))^(2) + z(Dpath(t))^(2))) → normIntegral(g, ax, ay) → LineintegralSum(Sequence[((Δt * f(x(path(k + Δt)), y(path(k + Δt)), z(path(k + Δt)))) * sqrt(x(Dpath(k + Δt))^(2) + y(Dpath(k + Δt))^(2) + z(Dpath(k + Δt))^(2))), k, ax, ay - Δt, Δt]) → RiemannTextfield(pathx) → InputBox1Textfield(pathy) → InputBox2Textfield(pathz) → InputBox3Textfield(f) → InputBox4Textfield(ax) → InputBox5Textfield(ay) → InputBox6CurveCartesian(pathx(i), pathy(i), i, ax, ay) → path2Derivative(path2) → Dpath2Simplify(sqrt(x(Dpath(t))^(2) + y(Dpath(t))^(2))) → norm2Integral(h, ax, ay) → Lineintegral2Sequence(path2(ax + (k * (ay - ax) / 100)), k, 0, 100, 1) → pointsSequence(path2(ax + (k * (ay - ax) / 100)) + (0, 0, 0), k, 0, 100, 1) → ptsSequence((x(Element[points, k]), y(Element[points, k]), F(x(Element[points, k]), y(Element[points, k]))), k, 1, 100 + 1, 1) → list1Sequence(Polygon[Element[pts, k], Element[list1, k], Element[list1, k + 1], Element[pts, k + 1], Element[pts, k]], k, 1, 100) → list2CurveCartesian(x(path(k)), y(path(k)), F(x(path(k)), y(path(k))), k, ax, ay) → SurfacecurveTextfield(F) → InputBox7