# Hyperbolic trig identity for tanh (2x) using exponential definitions

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• August 16th 2009, 11:04 PM
defcon3
Hyperbolic trig identity for tanh (2x) using exponential definitions
Hey,

Using exponential definitions, show that

tanh(2x)= (2tanh(x))/(1+tanh^2(x))

Please help. Thanks
• August 16th 2009, 11:26 PM
CaptainBlack
Quote:

Originally Posted by defcon3
Hey,

Using exponential definitions, show that

tanh(2x)= (2tanh(x))/(1+tanh^2(x))

Please help. Thanks

Start by writing down the exponential form for $\tanh(2x)$ then do the same for the right hand side. Now simplify what you have for the right hand side and with luck you will find that it is the same as you had for $\tanh(2x)$.

So try this and report back if you get stuck.

CB
• August 17th 2009, 12:21 AM
defcon3
its alrite i got it.. thanks alot