圆锥、圆柱与扇形的表面积相等关系(2D/3D动态演示)
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该范例通过二维与三维联动视图,直观演示圆锥、圆柱以及展开扇形三者表面积相等的几何关系。核心数学概念包括圆锥与圆柱的侧面积公式、扇形面积与弧长、以及立体图形的展开与表面积分解。作图要点:利用GeoGebra的Vector、Circle、Segment、Polygon、Cylinder、Angle、Cone、Circumference、Distance、PointIn、Plane、Rotate、CircleSector、CircleArc等命令,构建了可调节的圆锥与圆柱参数(如高度、半径),并通过动态对象(如滑块)控制尺寸,实时计算并比较表面积。适合高中或大学低年级学生学习立体几何、面积公式推导及动态数学建模,也可用于教师课堂演示或学生自主探索几何量之间的关系。
GeoGebra 命令及参数
Vector(W_i, O) → diameterVector(O, C_0) → rCircle(C_0, r_i, yAxis) → fVector(H_i, O) → h_yAxisDownVector(O, H_i) → h_YaxisUpSegment(O, H_i) → h_yAxisVector(EdgeOfCylinder, W_i) → v_1Vector(W_i, EdgeOfCylinder) → h_edgeSegment(H_i, EdgeOfCylinder) → dVector(EdgeOfCylinder, H_i) → diameter_revVector(H_i, EdgeOfCylinder) → u_1Polygon(O, H_i, EdgeOfCylinder, W_i) → Two_dCylinderRep, TwoDCylinderRep_3, TwoDCylinderRep_2, TwoDCylinderRep_1, TwoDCylinderRep_4Segment(C_0, C_h) → TwoDCylinderRep_hCircle(C_h, r_i, yAxis) → gCylinder((1 / 2 * w), (1 / 2 * w) + h, r_i) → Cylinder_1, c_i, c_h, CylinderSurfaceVector(W_i, C_h) → s_1Angle(C_0, W_i, C_h) → bVector(O, C_h) → s_2Segment(C_h, w) → sAngle(C_h, O, C_0) → b'Angle(O, C_h, w) → aVector(C_0, C_h) → Height_cylinderAngle(C_h, C_0, O, xOyPlane) → c'Angle(C_h, C_0, W_i) → cPolygon(C_h, O, W_i) → Two_dConeFrameAsTriangle, Hypotenuse2_dMiniTriangleL, TwoDCylinderRep_0, oCone(C_0, C_h, r_i) → Cone_i, c_iCone, ConeSurfaceCircumference(c_iCone) → pi_dConeCircle(circle_1, O, W_i) → circle_{2}SliceCircumference(circle_{2}Slice) → pi_dCircleEndDistance(C_h, circle_1) → slantSegment(O, C_0) → radiusConeCircumference(circle_{2}Slice) → pi_dCircleEndSliceCircle(C_h, slant, xOyPlane) → tCircumference(t) → pi_dCircleTPointIn(t) → PointtSegment(CutStart, C_h) → CompassLengthSegment(C_h, CutStart) → cutFromLinePlane(circle_{2}Slice) → plane_CircleRotate(CutStart, (-cutAngleMin), C_h) → CutFrom'Vector(C_h, CutStart) → vVector(C_h, CutFrom') → v'CircleSector(C_h, CutStart, CutFrom', xOyPlane) → sliceCircleArc(C_h, CutFrom', CutStart, xOyPlane) → ArcLengthDifferenceOfCircumferencesAngle(CutFrom', C_h, CutStart) → θCircleSector(C_h, CutFrom', CutStart, xOyPlane) → circle_2SliceInsideRotate(CutStart, (-ratio360deg), C_h) → CutDontCircleSector(C_h, CutDont, CutStart, xOyPlane) → eAngle(CutDont, C_h, CutStart, xOyPlane) → α