Homework Statement
verify these identities:
1) tanh^2 x + sech^2 x =1
2) sinh(x+y) = sinh cosh y + cosh x sinh y
Homework 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...