动态等边三角形与中值问题演示
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①本范例动态演示了Antonio Gutierrez在Twitter上提出的一个关于等边三角形、中值、指数函数、面积、余弦及菱形的问题;②涉及核心数学概念包括等边三角形构造、中位线性质、指数函数图像、面积计算、余弦定理、菱形特性;③作图要点提炼自GeoGebra命令:Polygon(多边形), Line(线), OrthogonalLine(垂线), Intersect(交点), Midpoint(中点), Segment(线段), Point(点), Rotate(旋转), Angle(角度), Ray(射线), Dilate(缩放), Min(最小值), Circle(圆), CircleSector(圆扇形), Vector(向量), Translate(平移);④适合高中数学教学,用于探究几何变换与函数结合问题。
GeoGebra 命令及参数
Polygon(A, B, 3) → poly1, f, g, h, CLine(C, A) → kOrthogonalLine(A, g) → iOrthogonalLine(B, h) → jIntersect(i, j) → DIntersect(h, j) → EMidpoint(C, B) → FSegment(C, F) → lPoint(l) → GRotate(G, 60°, D) → G'Angle(G, D, G') → αRay(D, G') → mIntersect(h, m) → HPolygon(H, G, C) → t1, c, h_1, g_1Polygon(A, B, G, H) → q1, a_1, b, g_2, h_2Angle(A, F, B) → βAngle(A, E, B) → γDilate(A, If[0 < d ≤ 1, 1 - d, 0], B) → A'Segment(A, A') → nRotate(A, If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], A) → A'_1Rotate(A', If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], A) → A''Segment(A'_1, A'') → n'Rotate(A'_1, If[2 < d ≤ 3, ((d - 2) * π / 3), π / 3], C) → IRotate(A'', If[2 < d ≤ 3, ((d - 2) * π / 3), π / 3], C) → A'''Segment(I, A''') → n''Dilate(A, If[3 < d ≤ 4, 4 - d, 0], F) → JSegment(A, J) → pDilate(B, If[4 < d ≤ 5, 5 - d, 0], D) → B'Segment(B, B') → qDilate(D, If[5 < d ≤ 6, 6 - d, 0], E) → D'Segment(D, D') → rSegment(C, A) → sSegment(D, G) → tSegment(D, H) → eSegment(C, G) → f_1Segment(C, H) → i_1Min({e, t, f_1, i_1}) → oCircle(C, (0.45 * o)) → c_1Intersect(s, i_1) → KIntersect(c_1, i_1, 1) → LRotate(L, If[9 < d ≤ 10, ((d - 9) * π / 3), π / 3], C) → L'CircleSector(C, L, L') → d_1Dilate(D, If[9 < d ≤ 10, 10 - d, 0], G) → D'_1Dilate(D, If[9 < d ≤ 10, 10 - d, 0], H) → D'_2Segment(D, D'_1) → j_1Segment(D, D'_2) → k_1Line(C, j_1) → l_1Line(C, k_1) → m_1Point(l_1) → MAngle(L, C, M) → δDilate(C, If[11 < d ≤ 12, 12 - d, 0], D) → C'Vector(C, C') → uTranslate(d_1, u) → e_1Rotate(e_1, If[11 < d ≤ 12, ((d - 11) * δ), δ], C') → p_1Dilate(C, If[12 < d ≤ 13, 13 - d, 0], H) → C'_1Dilate(G, If[12 < d ≤ 13, 13 - d, 0], C) → C'_2Dilate(H, If[12 < d ≤ 13, 13 - d, 0], G) → H'Segment(H, H') → n_1Segment(G, C'_2) → q_1Segment(C, C'_1) → r_1Polygon(H, G, C) → t2, c_2, h_3, g_3Angle(G, H, C) → εLine(A, B) → s_1Line(G, s_1) → t_1Point(t_1) → NAngle(H, G, N) → ζDilate(H, If[14 < d ≤ 15, 15 - d, 0], A) → H'_1Vector(H, H'_1) → vTranslate(H, v) → H'_2Translate(H, v) → H'_3Translate(H', v) → H''Segment(H'_3, H'') → b_1Rotate(H'_3, If[14 < d ≤ 15, ((d - 14) * ζ), ζ], H'_1) → ORotate(H'', If[14 < d ≤ 15, ((d - 14) * ζ), ζ], H'_1) → H'''Segment(O, H''') → f_2Dilate(H, If[15 < d ≤ 16, 16 - d, 0], H''') → H'_4Vector(H, H'_4) → wTranslate(C, w) → C'_3Translate(C'_1, w) → PSegment(C'_3, P) → i_2Rotate(C'_3, If[15 < d ≤ 16, ((-(d - 15)) * π / 3), ((-π)) / 3], P) → QRotate(P, If[15 < d ≤ 16, ((-(d - 15)) * π / 3), ((-π)) / 3], P) → P'Segment(Q, P') → j_2Dilate(C, If[16 < d ≤ 17, 17 - d, 0], Q) → G'_1Vector(C, G'_1) → u_1Translate(G, u_1) → G'_2Translate(C'_2, u_1) → RSegment(G'_2, R) → k_2Rotate(G'_2, If[16 < d ≤ 17, ((d - 16) * π / 3), π / 3], R) → SRotate(R, If[16 < d ≤ 17, ((d - 16) * π / 3), π / 3], R) → R'Segment(S, R') → l_2