旋转体体积(壳法)
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①本范例演示通过壳法计算旋转体体积的过程;②涉及核心数学概念包括积分、旋转体体积计算、函数图像;③构造要点:使用Line、Segment、CurveCartesian、Sequence、Textfield等命令绘制图形,涉及对象如e, aa, bb, n, ff, st, yDir, ss, f, Qss, Pss, PQ, gg, fInRotation, g, gInRotation, st2, lateralSurfAA, lateralSurfBB等;④适合高中及以上学生学习微积分和几何变换。
GeoGebra 命令及参数
Line((0, 0, 0), (0, 1, 0)) → yDirSegment(Pss, Qss) → PQCurveCartesian((t * cos(ss)), ff(t), (t * sin(ss)), t, aa, bb) → fInRotationCurveCartesian((t * cos(ss)), gg(t), (t * sin(ss)), t, aa, bb) → gInRotationSequence(Segment[((aa * cos(k)), gg(aa), (aa * sin(k))), ((aa * cos(k)), ff(aa), (aa * sin(k)))], k, 0, (2 * π), st2) → lateralSurfAASequence(Segment[((bb * cos(k)), gg(bb), (bb * sin(k))), ((bb * cos(k)), ff(bb), (bb * sin(k)))], k, 0, (2 * π), st2) → lateralSurfBBSequence(Segment[(t, gg(t), 0), (t, ff(t), 0)], t, aa, bb, st3) → regionSequence(Segment[((t * cos(ss)), gg(t), (t * sin(ss))), ((t * cos(ss)), ff(t), (t * sin(ss)))], t, aa, bb, st3) → regionInRotationSequence(Circle[(0, gg(aa + (k * st)), 0), aa + (k * st), yDir], k, 0, n, st1) → lowerCirclesSequence(Circle[(0, ff(aa + (k * st)), 0), aa + (k * st), yDir], k, 0, n, st1) → upperCirclesTextfield(ff) → InputBox1Textfield(gg) → InputBox2Textfield(aa) → InputBox3Textfield(bb) → InputBox4Textfield(st1) → InputBox5Textfield(st2) → InputBox6Sequence(Segment[(((tt + dx) * cos(k)), gg(tt), ((tt + dx) * sin(k))), (((tt + dx) * cos(k)), ff(tt), ((tt + dx) * sin(k)))], k, 0, (2 * π), stshell) → outerShellSequence(Segment[((tt * cos(k)), gg(tt), (tt * sin(k))), ((tt * cos(k)), ff(tt), (tt * sin(k)))], k, 0, (2 * π), stshell) → innerShellSequence(Circle[(0, ff(tt), 0), k, yDir], k, tt, tt + dx, stshell) → upperShellBaseTextfield(stshell) → InputBox8Textfield(tt) → InputBox9Textfield(gg) → InputBox7