Definitions of Conics: Dynamic Demonstration of Ellipse, Hyperbola, and Parabola
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Conics
This GeoGebra example dynamically illustrates the unified definition of conic sections (ellipse, hyperbola, parabola) as the locus of points whose ratio of distances to a fixed point (focus) and a fixed line (directrix) is constant. It covers core mathematical concepts such as focus, directrix, eccentricity, and the intersection of a plane with a cone. The construction uses commands like Circle, Point, Focus, Line, Ray, Distance, Angle, Rotate, Mirror, and Translate to build the 2D locus, while Cone, Plane, OrthogonalPlane, and IntersectPath create the 3D cross-section. Interactive buttons and sliders allow users to switch between conic types and adjust parameters. Suitable for high school or early college courses in analytic geometry and solid geometry, this example helps students grasp the geometric essence of conics and how eccentricity determines the curve type.
GeoGebra Commands & Parameters
Circle(H16, 4) → c16Point(c16) → M16LaTeX(S5, true, true) → text1Rotate(A6, ((n6 * 360))°, O6) → M6Segment(O6, M6) → s6Segment(F71, M7) → s71Segment(M7, F62) → s72Focus(e8) → F8, F'8Intersect(e8, j8) → I8, J8Intersect(m8_1, i8) → CIntersect(m8_1, i8) → DIntersect(m8_1, i8) → EIntersect(m8_1, i8) → F_1Intersect(e8, i8) → G8, H8Circle(F8, 11.5) → g8Ray(F8, H8) → h8Intersect(g8, h8) → A8,Segment(A8, H8) → k8Segment(F'8, H8) → m8Circle(F'8, 11.5) → p8Ray(F'8, I8) → n8Intersect(p8, n8) → C8,Segment(C8, I8) → q8Segment(I8, F8) → r8Segment(F8, A8) → f8Segment(F'8, C8) → f'8OrthogonalLine(D9, d9) → p9Segment(F9, D9) → s9LineBisector(D9, F9) → h9Intersect(p9, h9) → M9Intersect(h9, d9) → H9Segment(M9, F9) → f9Segment(M9, D9) → g9Intersect(s9, h9) → G9Polygon(E9, D9, N9) → t1, f, g, hIf(a9 > 0, Angle[H9, D9, M9], Angle[M9, D9, H9]) → αSegment(N9, M9) → iSegment(N9, M9) → l91Segment(F9, M9) → l92Segment(A10, B10) → jPoint(q_1) → C10Segment(A10, C10) → kSegment(C10, B10) → lLine(J, xAxis) → mPoint(m) → G10_1OrthogonalLine(G10_1, m) → nPoint(n) → H10_1Line(H10_1, l) → pIntersect(p, m) → I10_1Circle(G10_1, I10_1) → d10_1Intersect(d10_1, n) → G10_2, K10_1Line(K10_1, m) → qDistance(G10_1, H10_1) → r10Circle(F10, r10) → e10Intersect(e10, q) → H10_2, M10OrthogonalLine(M10, m) → sIntersect(m, s) → N10Segment(M10, N10) → tPolygon(B10, C10, A10) → t2, a10_1, b10, c10Polygon(I10_1, H10_1, G10_1) → t3, g10, i10, h10OrthogonalLine(H10, d10_2) → a10_2Intersect(d10_2, a10_2) → I10Point(d10_2) → K10Angle(K10, I10, H10) → γSegment(G10, H10) → a10Segment(H10, I10) → d10Segment(B12, A12) → f12Segment(C12, B12) → h12Point(i12) → G12OrthogonalLine(G12, i12) → j12Line(H12, h12) → k12Intersect(i12, k12) → N12Circle(G12, N12) → c122Intersect(c122, j12) → J12, K12Line(K12, i12) → l12Distance(G12, H12) → r12Circle(F, r12) → c121Intersect(c121, l12) → L12, M12OrthogonalLine(M12, i12) → m122Intersect(m122, i12) → GSegment(M12, G) → n12Segment(F, M12) → p12Polygon(A12, C12, B12) → t4, b12, a12, c12Segment(G12, N12) → h121Segment(K12, G12) → rSegment(H12, G12) → i121Mirror(L12, i12) → L12'Mirror(M12, i12) → M12'Mirror(G, (x(F), y(G))) → P'Segment(L12, P') → aSegment(L12, F) → dRotate(B13, t13, F13) → M13Segment(M13, F'12) → f13LineBisector(f13) → d131Line(F13, M13) → d132Intersect(d132, d131) → E13Segment(F13, M13) → f132Segment(E13, F'12) → f133Intersect(d131, f13) → A13Circle(F14, 5) → c14Point(c14) → B14Rotate(B14, t14, F14) → P14Segment(P14, F'14) → f_1LineBisector(f_1) → g14Line(F14, P14) → h14_1Intersect(g14, h14_1) → H14Segment(H14, F'14) → i_1Intersect(g14, f_1) → E14Angle(H14, E14, F'14) → εSegment(H14, P14) → g_1Segment(P15, F15) → h15_2OrthogonalLine(P15, h15_1) → j15_1LineBisector(h15_2) → k_1Intersect(k_1, j15_1) → H15_1Segment(H15_1, F15) → h15Segment(H15_1, P15) → j15Point(h15_1) → H15Angle(H15, P15, H15_1) → ζSegment(F14, P14) → h14Segment(M16, F16) → h_1LineBisector(h_1) → j_1Point(l14) → ISegment(I, H) → l_1LineBisector(l_1) → m_1Circle(A17, B17) → d_1LineBisector(F17, M17) → n_1Segment(F17, M17) → p_1Point(h15_1) → KAngle(K, P15, H15_1) → ηPlane(C5, (0, 0, 0), (0, 1, 0)) → b5Circle(C5, 3, b5) → c5Point(c5) → M5Segment(C5, M5) → f5OrthogonalPlane(C5, f5) → d5Cone((0, 0, -10), (0, 0, 0), 7) → e5, c, bCone((0, 0, -10), (0, 0, 0), 7) → h5, c_1, oCone((0, 0, -10), (0, 0, 0), 7) → g5, e_1, uMirror(e5, (0, 0, 0)) → e5'IntersectPath(d5, e5) → k5IntersectPath(d5, e5') → p5LaTeX(M5, true, true) → text30Circle(F13, 6) → eDistance(A, C) → ACDistance(A, B) → AB