Elliptic Plane: Half Sphere to Möbius Strip
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This example demonstrates the construction of a Möbius strip from a specific region on a hemisphere, visually illustrating the geometric properties of the elliptic plane. Key mathematical concepts include spherical geometry, geometric transformations, and topology basics. The construction utilizes GeoGebra commands and objects such as CircumcircleArc, Circle, Line, Sphere, Intersect, Polygon, Semicircle, Segment, Plane, IntersectPath, Point, CurveCartesian, Surface, Angle, Rotate, Mirror to dynamically generate the figure. Suitable for high school students and math enthusiasts studying spatial geometry and topological transformations.
GeoGebra Commands & Parameters
CircumcircleArc((0, 0, -1), (0, 1, 0), (0, 0, 1)) → dCircle(P, π, xOyPlane) → cLine(P, yAxis) → fSphere(P, π / 2) → gIntersect(f, g) → G, HSphere(G, Width / 2) → jLine(H, zAxis) → iLine(G, zAxis) → hIntersect(h, j) → I, JLine(I, f) → nIntersect(n, i) → KLine(J, f) → kIntersect(i, k) → LPolygon(I, K, L, J) → Rectangle, i_1, k_4, l_1, j_1Intersect(xOyPlane, Rectangle) → S, ULine(S, U) → lIntersect(zAxis, xAxis) → FSemicircle(O, N, xOyPlane) → EquatorLineSphereSphere(F, P) → eSegment(G, H) → qLine(N, q) → f_1Plane(f_1, zAxis) → p_1IntersectPath(p_1, e) → rPoint(d) → MPlane(M, xAxis) → q_1IntersectPath(q_1, e) → FullLineIntersect(FullLine, r, 2) → QCircumcircleArc(Q, P, M) → LineSphere_1Point(LineSphere_1) → S_SPlane(S_S, zAxis) → r_1Intersect(r_1, EquatorLineSphere) → R, TCurveCartesian(cos(t), sin(t), 0, t, 0, (2 * π)) → EquatorLineMobiusPoint(EquatorLineMobius) → BPoint(EquatorLineMobius) → CPoint(EquatorLineMobius) → DPoint(EquatorLineMobius) → ESurface((cos(u) * cos(v)), (cos(u) * sin(v)), sin(u), u, 0, (2 * π), v, 0, π) → SphereCurveCartesian(((1 + (Distance * cos(t / 2))) * cos(t)), ((1 + (Distance * cos(t / 2))) * sin(t)), (Distance * sin(t / 2)), t, 0, (4 * π)) → EquidistantPoint(EquatorLineSphere) → AAngle(N, F, A, xOyPlane) → αCircle(P, α, xOyPlane) → pCircle(P, (2 * π) - α, xOyPlane) → p2Surface(1 + (v * cos(u)), u, (v * sin(u)), u, ((-π)) / 2, π / 2, v, ((-Width)) / 2, Width / 2) → TwistedSurface(sin(u), (cos(u) * cos(v)), (cos(u) * sin(v)), u, 0, π, v, 0, π) → HalfSphereRotate(N, (2 * α), F, xOyPlane) → A_mAngle(N, F, A_m, xOyPlane) → δAngle(R, F, S_S) → γAngle(Q, F, S_S, q_1) → βAngle(q_1, xOyPlane) → εCurveCartesian(sin(u), (cos(u) * cos(ε)), (cos(u) * sin(ε)), u, 0, π) → LineSphereSurface(1 - (v * sin((Twisting * u))), u - π / 2, (v * cos((Twisting * u))), u, 0, π, v, ((-Width)) / 2, Width / 2) → TwistSurface(((-cos(u)) * sin(v)), (cos(u) * cos(v)), sin(u), u, (-atan(Width / 2)) - π, atan(Width / 2) - π, v, 0, π) → SphericalStripSurface(((1 - Flattening) * ((-cos(u)) * sin(v))) + Flattening, (((1 - Flattening) * cos(u)) * cos(v)) + (Flattening * (v - π / 2)), ((1 - Flattening) * sin(u)) + (Flattening * tan((-u) + π)), u, (-atand(Width / 2)) - π, atand(Width / 2) - π, v, 0, π) → FlattenSurface(1 + (v * cos(u)), ((1 + Prolonging) * u), (v * sin(u)), u, ((-π)) / 2, π / 2, v, ((-Width)) / 2, Width / 2) → ProlongTwistedSurface(1 + (v * cos(u / 2)), u, (v * sin(u / 2)), u, (-π), π, v, ((-Width)) / 2, Width / 2) → ProlongedSurface(((1 + (v * cos(u / 2))) * cos(u)), ((1 + (v * cos(u / 2))) * sin(u)), (v * sin(u / 2)), v, ((-Width)) / 2, Width / 2, u, 0, (2 * π)) → MobiusStripSurface(((1 + (v * cos(u / 2))) * cos((Glueing * u))), ((1 - Glueing) * u) + ((Glueing * (1 + (v * cos(u / 2)))) * sin((Glueing * u))), (v * sin(u / 2)), u, (-π), π, v, ((-Width)) / 2, Width / 2) → GlueCurveCartesian(1, u - π / 2, (-tan(asin((cos(u) * sin(ε))))), u, 0, π) → LineRectangleCurveCartesian(1 - (tan(asin((cos(u - π / 2) * sin(ε)))) * cos(u)), u, ((-tan(asin((cos(u - π / 2) * sin(ε))))) * sin(u)), u, ((-π)) / 2, π / 2) → LineTwistedCurveCartesian(1 - (tan(asin((cos(u / 2 - π / 2) * sin(ε)))) * cos(u / 2)), u, ((-tan(asin((cos(u / 2 - π / 2) * sin(ε))))) * sin(u / 2)), u, (-π), π) → LineProlongedCurveCartesian(((1 - (tan(asin((cos(u / 2 - π / 2) * sin(ε)))) * cos(u / 2))) * cos(u)), ((1 - (tan(asin((cos(u / 2 - π / 2) * sin(ε)))) * cos(u / 2))) * sin(u)), ((-tan(asin((cos(u / 2 - π / 2) * sin(ε))))) * sin(u / 2)), u, (-π), π) → LineMobiusIntersectPath(xOyPlane, Rectangle) → EquatorLineRectangleIntersect(xOyPlane, p2) → V,Intersect(l, c) → W, ZSegment(W, Z) → EquatorLineProlongedCircle(F, 1, xOyPlane) → EquatorMirror(S_S, F) → S'Mirror(A, F) → A'
AI Drawing Prompt Reference
Draw a hemisphere with a semicircle on its surface as the equator. Start from a specific region on the equator and transform it through rotations and reflections to create a Möbius strip. The final image should illustrate the geometric transformation from the hemisphere to the Möbius strip, highlighting spherical geometry, geometric construction, and basic topological concepts.
The prompt above was compiled from the original drawing commands and is for reference only.