Cone, Cylinder & Sector with Equal Surface Area (2D/3D)
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This GeoGebra example demonstrates the geometric relationship where the surface areas of a cone, a cylinder, and a circular sector are equal, using linked 2D and 3D representations. The core mathematical concepts include lateral surface area formulas for cones and cylinders, sector area and arc length, and the unfolding of 3D solids into 2D nets. The construction employs GeoGebra commands such as Vector, Circle, Segment, Polygon, Cylinder, Angle, Cone, Circumference, Distance, PointIn, Plane, Rotate, CircleSector, and CircleArc, along with dynamic objects like sliders to adjust height and radius, enabling real-time comparison of computed areas. This resource is suitable for high school or early college students studying solid geometry, area derivations, and dynamic mathematical modeling, and serves as an excellent tool for classroom demonstrations or independent exploration of geometric relationships.
GeoGebra Commands & Parameters
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