The hyperbolic law of sines relates the sides and angles of a hyperbolic triangle. For curvature , let
,
, and
be the side lengths opposite
,
, and
, respectively. Then
Here
is the hyperbolic sine. For curvature
, the formula becomes
As ,
the curvature approaches zero and
, so the common factor
cancels and the formula reduces to the Euclidean law
of sines.