Editing Hyperbolic triangle (section)

===General trigonometry===
Whether ''C'' is a right angle or not, the following relationships hold:
The [[hyperbolic law of cosines]] is as follows:
:<math>\cosh c=\cosh a\cosh b-\sinh a\sinh b \cos C,</math>

Its [[duality (projective geometry)|dual theorem]] is
:<math>\cos C= -\cos A\cos B+\sin A\sin B \cosh c,</math>

There is also a ''law of sines'':
:<math>\frac{\sin A}{\sinh a} = \frac{\sin B}{\sinh b} = \frac{\sin C}{\sinh c},</math>

and a four-parts formula:
:<math>\cos C\cosh a=\sinh a\coth b-\sin C\cot B</math>
which is derived in the same way as the [[Spherical_trigonometry#Cotangent_four-part_formulae|analogous formula in spherical trigonometry]].

<!--- still in development
====Solving Hyperbolic triangles====
see also [[Solving triangles]]
*'''''Angle - Angle - Angle''''' use the dual form of the hyperbolic law of cosines
*'''''Angle - Angle - Side''''' use hyperbolic law of sines to get to Angle - Angle - Side -side
*'''''Angle - Angle - Side -side ''''' use the four-parts formula
*'''''Angle - Side - Angle'''''
*'''''Angle - Side - side''''' use hyperbolic law of sines to get to Angle - Angle - Side -side
*'''''Side - Angle - Side'''''
*'''''Side - Side - Side''''' use the hyperbolic law of cosines
end of still in development ---->