1. The problem statement, all variables and given/known data verify these identities: 1) tanh^2 x + sech^2 x =1 2) sinh(x+y) = sinh cosh y + cosh x sinh y 2. Relevant equations cosh2x - sinh2x = 1 sech2x + tanh2x = 1 coth2x - csch2x = 1 sinh (x ± y) = sinh x cosh y ± cosh x sinh y cosh (x ± y) = cosh x cosh y ± sinh x sinh y tanh(x ± y) = (tanh x ± tanh y)/(1 ± tanh x.tanh y) coth(x ± y) = (coth x coth y ± l)/(coth y ± coth x)