Editing Penrose triangle (section)

==Description==
[[File:Penrose-triangle-4color-rotation.gif|thumb|A rotating Penrose triangle model to show illusion. At the moment of illusion, there appears to be a pair of purple faces (one partially occluded) joined at right angles, but these are actually parallel faces, and the partially occluded face is internal, not external.]]
The tribar/triangle appears to be a [[solid]] object, made of three straight beams of square cross-section which meet pairwise at right angles at the vertices of the [[triangle]] they form. The beams may be broken, forming cubes or cuboids.

This combination of properties cannot be realized by any three-dimensional object in ordinary [[Euclidean space]]. Such an object can exist in certain Euclidean [[3-manifold]]s.{{r|francis}} A surface with the same [[geodesic distance]]s as the depicted surface of the tribar, but without its flat shape and right angles, are to be preserved, can also exist in 5-dimensional Euclidean space, which is the lowest-dimensional Euclidean space within which this surface can be isometrically embedded.<ref name=zeng/> There also exist three-dimensional solid shapes each of which, when viewed from a certain angle, appears the same as the 2-dimensional depiction of the Penrose triangle, such as the sculpture "Impossible Triangle" in [[East Perth]], Australia.{{r|wa}} The term "Penrose Triangle" can refer to the 2-dimensional depiction or the impossible object itself.

If a line is traced around the Penrose triangle, a 4-loop [[Möbius strip]] is formed.{{r|gardner}}