立方体上的三角形
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①本范例演示如何在立方体表面构建三角形;②涉及核心数学概念包括立体几何、几何作图、向量与坐标几何;③构造过程中运用了点、立方体、点在对象内判断、旋转、线段、交点、条件判断等GeoGebra命令与对象;④适合高中及以上学生用于学习空间几何与几何作图方法。
GeoGebra 命令及参数
Point(Circle[B_2, Distance[A_2, B_2], Segment[A_2, B_2]]) → C_2Cube(A_2, B_2, C_2) → a, D, faceCDHG, faceEFGH, edgeAD, edgeAB, edgeBC, edgeCD, edgeAE, edgeDH, edgeEH, edgeEF, E, edgeBF, edgeFG, edgeCG, edgeGH, F, G, H, faceABCD, faceADHE, faceABFE, faceBCGFPointIn(faceEFGH) → BPointIn(faceABFE) → APointIn(faceCDHG) → CRotate(B, 90°, edgeEF) → I'Segment(A, I') → fIntersect(f, edgeEF) → LRotate(B, 90°, edgeFG) → I'_1Rotate(A, (-(90°)), edgeBF) → J'Segment(I'_1, J') → gIntersect(g, edgeFG) → MIntersect(g, edgeBF) → NRotate(C, 90°, edgeCG) → K'Segment(J', K') → iRotate(C, (-(90°)), edgeGH) → K'_1Rotate(C, 90°, edgeDH) → K'_2Rotate(C, 90°, edgeCD) → K'_3Rotate(A, -90°, edgeEF) → J'_1Rotate(A, 90°, edgeAB) → J'_2Rotate(A, 90°, edgeAE) → J'_3Segment(J'_1, K'_1) → jSegment(J'_3, K'_2) → kSegment(J'_2, K'_3) → lIntersect(i, edgeBF) → OIntersect(i, edgeCG) → PIntersect(edgeEF, j) → QIntersect(edgeGH, j) → RIntersect(edgeDH, k) → SIntersect(k, edgeAE) → TIntersect(edgeCD, l) → UIntersect(edgeAB, l) → VIf(ii, PolyLine[A, O, P, C], If[ll, PolyLine[A, V, U, C], If[jj, PolyLine[A, Q, R, C], PolyLine[A, T, S, C]]]) → mRotate(B, 90°, edgeGH) → I'_2Segment(C, I'_2) → nRotate(B, 90°, edgeFG) → I'_3Rotate(C, 90°, edgeCG) → K'_4Segment(I'_3, K'_4) → pRotate(C, 90°, edgeDH) → K'_5Rotate(B, 90°, edgeEH) → I'_4Segment(I'_4, K'_5) → qIntersect(edgeEH, q) → WIntersect(edgeDH, q) → ZIntersect(edgeGH, n) → A_1Intersect(p, edgeFG) → B_1Intersect(edgeCG, p) → C_1If(nn, PolyLine[C, A_1, B], If[pp, PolyLine[C, C_1, B_1, B], PolyLine[C, Z, W, B]]) → rRotate(B, 90°, edgeEH) → I'_5Segment(I'_5, J'_3) → sIntersect(edgeEH, s) → D_1Intersect(edgeAE, s) → E_1If(ff, PolyLine[A, L, B], If[gg, PolyLine[A, N, M, B], PolyLine[A, E_1, D_1, B]]) → h