[color=#999999][color=#999999][color=#999999]This activity belongs to the [i]GeoGebra book[/i] [url=https://www.geogebra.org/m/h3gbmymu]Linkages[/url].[/color][/color][/color][br][br]Since three-dimensional space has one more dimension than the plane, the constraint imposed by the fixed length of each bar is weaker, which gives the mechanism greater freedom. While [url=https://www.geogebra.org/m/h3gbmymu#material/sj6npzsa]our flat rhombus[/url] had 1 internal degree of freedom, its spatial version has 2, as we can see in this construction. This implies that even the very idea of a rhombus as a "parallelogram" loses its meaning. Instead, it is better to think of a hinge.[br][br]Note that now, to match the total number of degrees of freedom with the number of internal degrees of freedom, in addition to fixing points O and U, we have also fixed the plane in which point E is held.

Now, although the construction transmits the movement from F to E and vice versa, it is not comfortable to handle. On this occasion, it is more practical to preserve the dependence of F on E, so that when F moves point E remains in its position. This is what the following construction does, typical of Dynamic Geometry (without scripts).

[color=#999999]Author of the construction of GeoGebra: [color=#999999][url=https://www.geogebra.org/u/rafael]Rafael Losada[/url][/color][/color]