Volume by Cylindrical Shells - Example sin(x^2)

Volume by Cylindrical Shells - Example sin(x^2)
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2016-03-14 11:18
This example demonstrates the volume of a solid of revolution using the method of cylindrical shells for the function sin(x^2). It covers the application of integration in geometry, including the cylindrical shell method and volume calculation. It uses commands like Sequence, Surface, Polygon, Segment in GeoGebra, suitable for high school mathematics education.

GeoGebra Commands & Parameters

  1. Sequence(a + ((k - 0.5) * dx), k, 1, n) → midpts
  2. Sequence(a + (k * dx), k, 0, n - 1) → leftpts
  3. Sequence(a + (k * dx), k, 1, n) → rightpts
  4. Sequence(Polygon[(xk(k - 1), y_B(Element[evalpts, k])), (xk(k - 1), y_T(Element[evalpts, k])), (xk(k), y_T(Element[evalpts, k])), (xk(k), y_B(Element[evalpts, k]))], k, 1, n) → Rectangles
  5. Sequence((Element[evalpts, k], 0), k, 1, n) → evalptsplot
  6. Surface(xrot + ((xk(k - 1) - xrot) * cos(t)), h, ((xk(k - 1) - xrot) * sin(t)), t, 0, (2 * π), h, y_B(Element[evalpts, k]), y_T(Element[evalpts, k])) → ShellIn_k
  7. Surface(xrot + (r * cos(t)), y_T(Element[evalpts, k]), (r * sin(t)), t, 0, (2 * π), r, xk(k - 1) - xrot, xk(k) - xrot) → UpShell_k
  8. Surface(xrot + ((xk(k) - xrot) * cos(t)), h, ((xk(k) - xrot) * sin(t)), t, 0, (2 * π), h, y_B(Element[evalpts, k]), y_T(Element[evalpts, k])) → ShellOut_k
  9. Surface(xrot + (r * cos(t)), y_B(Element[evalpts, k]), (r * sin(t)), t, 0, (2 * π), r, xk(k - 1) - xrot, xk(k) - xrot) → ShellDown_k
  10. Sequence(Surface[xrot + ((xk(k - 1) - xrot) * cos(t)), h, ((xk(k - 1) - xrot) * sin(t)), t, 0, (2 * π), h, y_B(Element[evalpts, k]), y_T(Element[evalpts, k])], k, 1, n) → ShellsIn
  11. Sequence(Surface[xrot + (r * cos(t)), y_T(Element[evalpts, k]), (r * sin(t)), t, 0, (2 * π), r, xk(k - 1) - xrot, xk(k) - xrot], k, 1, n) → ShellsUp
  12. Sequence(Surface[xrot + (r * cos(t)), y_B(Element[evalpts, k]), (r * sin(t)), t, 0, (2 * π), r, xk(k - 1) - xrot, xk(k) - xrot], k, 1, n) → ShellsDown
  13. Sequence(Surface[xrot + ((xk(k) - xrot) * cos(t)), h, ((xk(k) - xrot) * sin(t)), t, 0, (2 * π), h, y_B(Element[evalpts, k]), y_T(Element[evalpts, k])], k, 1, n) → ShellsOut
  14. Surface(xrot + (cos((-t)) * (u - xrot)), y_B(u), (sin((-t)) * (u - xrot)), u, a, b, t, 0, RotationAngle) → Solid_B
  15. Surface(xrot + (cos((-t)) * (u - xrot)), y_T(u), (sin((-t)) * (u - xrot)), u, a, b, t, 0, RotationAngle) → Solid_T
  16. Surface(xrot + ((a - xrot) * cos((-t))), h, ((a - xrot) * sin((-t))), t, 0, RotationAngle, h, y_B(a), y_T(a)) → Solid_a
  17. Surface(xrot + ((b - xrot) * cos((-t))), h, ((b - xrot) * sin((-t))), t, 0, RotationAngle, h, y_B(b), y_T(b)) → Solid_b
  18. Surface(xrot + (cos((-RotationAngle)) * (u - xrot)), ((1 - w) * y_B(u)) + (w * y_T(u)), (sin((-RotationAngle)) * (u - xrot)), w, 0, 1, u, a, b) → Solid_e
  19. Surface(xrot + u - xrot, ((1 - w) * y_B(u)) + (w * y_T(u)), (0 * (u - xrot)), w, 0, 1, u, a, b) → region3d
  20. Polygon((xk(k - 1), y_B(Element[evalpts, k])), (xk(k - 1), y_T(Element[evalpts, k])), (xk(k), y_T(Element[evalpts, k])), (xk(k), y_B(Element[evalpts, k]))) → Rectangle_k, f, g, h, i
  21. Segment((0, 0), (xrot, 0)) → c