Posted by jh on Monday, March 22, 2010 at 4:05am.
Can anyone help me with this question please!!
Show that
(cosh x)^2  (sinh x)^2 = 1
for every real number x.

Precalculus  MathMate, Monday, March 22, 2010 at 8:24am
Expand and simplify using:
cosh(x)=(e^{x}+e^{x})/2
sinh(x)=(e^{x}e^{x})/2
noting that e^{x} * e^{x}=1
For the domain, since both e^{x} and e^{x} have a domain of R, so the expression cosh(x)²sinh(x)²=1
also has a domain of R, or (∞,&infin).