Editing Reuleaux triangle (section)

=== In nature ===
[[File:Reuleaux foam.svg|thumb|upright|The Reuleaux triangle as the central bubble in a mathematical model of a four-bubble planar soap bubble cluster]]
According to [[Plateau's laws]], the circular arcs in two-dimensional [[soap bubble]] clusters meet at 120° angles, the same angle found at the corners of a Reuleaux triangle. Based on this fact, it is possible to construct clusters in which some of the bubbles take the form of a Reuleaux triangle.<ref name="foam">{{citation
 | last1 = Modes | first1 = Carl D.
 | last2 = Kamien | first2 = Randall D.
 | arxiv = 0810.5724
 | doi = 10.1039/c3sm51585k
 | issue = 46
 | journal = [[Soft Matter (journal)|Soft Matter]]
 | pages = 11078–11084
 | title = Spherical foams in flat space
 | volume = 9
 | year = 2013| bibcode = 2013SMat....911078M
 | s2cid = 96591302
 }}.</ref>

The shape was first isolated in crystal form in 2014 as Reuleaux triangle disks.<ref>{{citation |first1=C. H. B. |last1= Ng |first2=W. Y. |last2=Fan |title=Reuleaux triangle disks: New shape on the block |journal=[[Journal of the American Chemical Society]] |volume=136 |issue=37 |year=2014 |pages=12840–12843 |doi=10.1021/ja506625y|pmid= 25072943 |bibcode= 2014JAChS.13612840N }}.</ref> Basic [[bismuth nitrate]] disks with the Reuleaux triangle shape were formed from the [[hydrolysis]] and [[precipitation]] of bismuth nitrate in an ethanol–water system in the presence of 2,3-bis(2-pyridyl)pyrazine.