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Polyhedra 3D Viewer

Explore Platonic and Archimedean solids in 3D. Rotate, unfold to nets, and verify Euler formula V-E+F=2.

Tested tool guide Tested browser tools Checked August 16, 2026

What Polyhedra 3D Viewer does, with a checked example

Eighteen convex solids whose vertices all look the same: the five Platonic solids, one regular polygon per face, and the thirteen Archimedean solids, which mix two or three face types. Drag any model to rotate it, unfold it into a flat net, and read off vertex, edge, and face counts with the Euler check V - E + F = 2. What surprises most people: a solid has no single net. The viewer unfolds one of many - a cube alone has 11 distinct nets - and the two snub solids come in mirror-image pairs.

Worked example

A concrete input and expected output from the current implementation.

Input

Octahedron (picked from the list of five Platonic solids)

Expected output

The octahedron renders as a rotatable 3D model with the readout V = 6, E = 12, F = 8 and the Euler check 6 - 12 + 8 = 2, marked as satisfied.

Every octahedron has 6 vertices, 12 edges, and 8 triangular faces, with 4 triangles meeting at each vertex. The counts satisfy V - E + F = 2 because the octahedron is convex, which is exactly the condition the Euler check requires.

How the result is produced

1

The solid set

The viewer carries the five Platonic and thirteen Archimedean solids. Each solid has exact geometry - vertex positions and the regular polygons that meet there - so the displayed V, E, F counts are the true counts, from the tetrahedron's 4 vertices to the truncated icosidodecahedron's 120. You rotate the model in three dimensions; a readout shows the counts and the Euler expression.

2

Unfolding to a net

The unfold action hinges the faces outward around shared edges until the surface lies flat in one plane, showing how the solid is stitched together. The cut pattern is chosen by the viewer, and it is not unique: cutting a different set of edges produces a different net. A cube, for example, has 11 distinct nets, and the displayed one is just one of them.

Good uses

  • Verify a hand count. After counting a dodecahedron yourself, check the readout: 20 vertices, 30 edges, 12 faces, and 20 - 30 + 12 = 2.
  • Plan a paper model. Unfold the icosahedron to see all 20 triangles laid flat, so the edge connections are clear before you cut card stock.
  • Tell similar Archimedean solids apart. The truncated cube (8 triangles, 6 octagons) and the truncated octahedron (6 squares, 8 hexagons) are easy to confuse in a drawing; rotating each shows which polygons meet at a vertex.

Limits and checks

  • Euler's formula only covers sphere-shaped polyhedra. All 18 solids here are convex, so the check passes every time; for a donut-shaped polyhedron V - E + F would be 0. Do not read the check as something that distinguishes one solid from another.
  • Faces share edges and vertices, so summing face sides double-counts. The icosahedron's 20 triangles have 60 sides total, but each edge belongs to two triangles, giving 30 edges, and the tool counts each edge once.
  • The net is one unfolding among many. The viewer decides which edges to cut, and different cuts give different nets; the cube alone has 11, so the layout shown is an example, not the canonical one.

Common questions

What makes a solid Archimedean instead of Platonic?

A Platonic solid uses one kind of regular face, all triangles or all squares or all pentagons, with the same arrangement at every vertex. An Archimedean solid mixes two or three regular face types, like the pentagons and hexagons of the truncated icosahedron, while every vertex still looks identical. There are 5 Platonic and 13 Archimedean solids, and the viewer lists all 18.

Why does the Euler check pass for every solid?

Because V - E + F = 2 is a theorem for every convex polyhedron, and all 18 solids here are convex, the equality holds exactly each time, for instance 120 - 180 + 62 = 2 for the truncated icosidodecahedron. The readout is a consistency check on the counts, not a filter that selects solids.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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