Difference of Squares of Hyperbolic Cosine and Sine

Theorem

 * $\cosh^2 x - \sinh^2 x = 1$

where $\cosh$ and $\sinh$ are hyperbolic cosine and hyperbolic sine.

Also presented as
This result can also be presented as:
 * $\cosh^2 x = 1 + \sinh^2 x$

or:
 * $\sinh^2 x = \cosh^2 x - 1$

Also see

 * Sum of Squares of Sine and Cosine