Proving the Hyperbolic Function Identity (1+tanhx)/(1-tanhx)=e^(2x)

In summary, the conversation is about proving the equation (1+tanhx)/(1-tanhx)=e^(2x). The attempt at a solution involved substituting different forms of tanhx, but the solution was found by simplifying (1 + sinhx/coshx)/(1 - sinhx/coshx) and simplifying to e^2x.
  • #1
Pietair
59
0

Homework Statement


Prove that:
(1+tanhx)/(1-tanhx)=e^(2x)

Homework Equations



09368019eae4f200d4ed8e266bfa50dc.png


The Attempt at a Solution



I tried substituting tanhx for (e^x-e^(-x))/(e^x+e^(-x)) and for (e^(2x)-1)/(e^(2x)+1))

But I really have no clue how to continue...
 
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  • #2
Hi Pietair! :smile:

Hint : (1+tanhx)/(1-tanhx) = (1 + sinhx/coshx)/(1 - sinhx/coshx) = … ? :wink:
 
  • #3
Thanks for your answer but it still doesn't make sense.

I don't know how to rewrite it to something more "common".
 
  • #4
Pietair said:
Thanks for your answer but it still doesn't make sense.

I don't know how to rewrite it to something more "common".

try simplifying (1 + sinhx/coshx)/(1 - sinhx/coshx) …

get rid of the internal fractions :wink:
 
  • #5
(coshx+sinhx)/(coshx-sinhx)

= (0.5e^x+0.5e^(-x)+0.5e^x-0.5e^(-x))/((0.5e^x+0.5e^(-x)-0.5e^x+0.5e^(-x))

= e^x/e^(-x)

= e^2x (proven)

Thanks a lot!
 

1. What is a hyperbolic function?

A hyperbolic function is a type of mathematical function that is defined by the relationship between the exponential function and the trigonometric functions. They are useful in solving problems related to curves and surfaces.

2. Why are hyperbolic functions important?

Hyperbolic functions have numerous applications in physics, engineering, and other branches of science. They are used to model real-life situations such as the shape of a hanging cable or the motion of a pendulum. They also have connections to other areas of mathematics, such as complex analysis and differential equations.

3. How are hyperbolic functions related to exponential and trigonometric functions?

Hyperbolic functions are defined in terms of the exponential function and the trigonometric functions. The hyperbolic sine and cosine functions are defined as combinations of the exponential function and the sine and cosine functions, respectively. Other hyperbolic functions, such as the hyperbolic tangent and cotangent, are also defined in terms of these basic functions.

4. What is the proof of the hyperbolic function identities?

The proof of the hyperbolic function identities involves using the definitions of the hyperbolic functions and the properties of the exponential and trigonometric functions. By manipulating these definitions and properties, we can show that the hyperbolic function identities hold true for all values of the variables involved.

5. Are there any practical uses for hyperbolic function proofs?

While the proofs of hyperbolic function identities may not have direct practical applications, understanding and using these identities can be extremely helpful in solving real-world problems. They also provide a deeper understanding of the relationship between different mathematical functions and can be used to derive other useful formulas and equations.

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