About: http://webisa.webdatacommons.org/368509065

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	This makes the argument valid everywhere except at the origin, which is OK since the partial derivative is clearly undefined there anyway, since at the origin $ heta$ can be any angle.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com