Hyperbolic Tangent of Sum/Corollary

Corollary to Hyperbolic Tangent of Sum

 * $\tanh \left({a - b}\right) = \dfrac {\tanh a - \tanh b} {1 - \tanh a \tanh b}$

where $\tanh$ denotes the hyperbolic tangent.

Proof
{{eqn | l = \tanh \paren {a - b}     | r = \frac {\tanh a + \tanh \paren {-b} } {1 + \tanh a \tanh \paren {-b} | c = Hyperbolic Tangent of Sum }}