双W桁架
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①本范例演示双W桁架的结构与几何特性;②涉及的核心数学概念包括几何作图、角度计算、线段与直线关系;③作图要点:运用了Rotate(旋转)、Line(直线)、Segment(线段)、OrthogonalLine(垂线)、Intersect(交点)、Angle(角度)等GeoGebra命令;④适合高中及以上学生学习桁架结构、几何建模及空间几何知识。
GeoGebra 命令及参数
Rotate(A_2, 120°, B_2) → A'_1Line(B_2, A_2) → f_2Line(B_2, A'_1) → g_2Line(A_2, A'_1) → h_2Segment(A_2, B_2) → i_2Segment(B_2, A'_1) → j_2Segment(A'_1, A_2) → k_2OrthogonalLine(B_2, k_2) → a_2Rotate(A_2, 30°, B_2) → A_1Line(B_2, A_1) → f_1Rotate(A'_1, (-(30°)), B_2) → E_1Line(B_2, E_1) → j_1Rotate(A'_1, (-(45°)), B_2) → CRotate(A_2, 45°, B_2) → DLine(B_2, D) → fLine(B_2, C) → gIntersect(f, k_2) → EIntersect(g, k_2) → FIntersect(j_2, k_2) → GIntersect(g, k_2) → HIntersect(j_2, k_2) → IRotate(A'_1, 70°, F) → JAngle(A'_1, F, J) → γRotate(A_2, (-(70°)), E) → KAngle(K, E, A_2) → δLine(E, K) → hLine(F, J) → iIntersect(h, i_2) → LIntersect(i, j_2) → MRotate(A'_1, (-(20°)), M) → NAngle(N, M, A'_1) → εRotate(A_2, 20°, L) → OAngle(A_2, L, O) → ζLine(L, O) → jLine(M, N) → kIntersect(j, k_2) → PIntersect(k, k_2) → QOrthogonalLine(P, k_2) → lOrthogonalLine(Q, k_2) → mSegment(P, L) → pSegment(E, L) → qSegment(E, B_2) → rSegment(F, B_2) → sSegment(F, M) → tSegment(M, Q) → aAngle(F, E, B_2) → ηAngle(B_2, F, E) → θOrthogonalLine(Q, j_2) → nOrthogonalLine(P, i_2) → bIntersect(b, i_2) → RIntersect(n, j_2) → SSegment(P, R) → cSegment(Q, S) → dAngle(A_2, R, P) → ιAngle(Q, S, A'_1) → κ