The Student Room Group

Prove this hyperbolic equation

sinh^2(x) - sinh^2(y) = sinh(x+y)sinh(x-y)
Reply 1
Have you tried expanding both sides and seeing if you can equate them?
Original post by Lies and Lies
sinh^2(x) - sinh^2(y) = sinh(x+y)sinh(x-y)


I'd express the right hand exponentially.
Original post by Kvothe the Arcane
I'd express the right hand exponentially.


doing the RHS becomes incredibkly complex
Original post by offhegoes
Have you tried expanding both sides and seeing if you can equate them?


You can't do that - he needs go from LHS to RHS as he is proving they are equal.
Original post by Kvothe the Arcane
I'd express the right hand exponentially.


Notice the forum this is posted in lol... Move it to the maths one :tongue:
Original post by offhegoes
Have you tried expanding both sides and seeing if you can equate them?


yep doesn't seem to get anywhere
Original post by RDKGames
You can't do that - he needs go from LHS to RHS as he is proving they are equal.


Notice the forum this is posted in lol... Move it to the maths one :tongue:

No I can go either way
Original post by Lies and Lies
yep doesn't seem to get anywhere


Post some working then.

I would expand both sides.

The RHS only really gets messy is you expand ex+ye^{x+y} to exeye^xe^y, etc., so don't - just multply the sinhs together in exponential form. Just remember your rules for indices.
Original post by ghostwalker
Post some working then.

I would expand both sides.

The RHS only really gets messy is you expand ex+ye^{x+y} to exeye^xe^y, etc., so don't - just multply the sinhs together in exponential form. Just remember your rules for indices.


IMG_20161126_191309.jpg
Reply 9
Original post by RDKGames
You can't do that - he needs go from LHS to RHS as he is proving they are equal.


There is absolutely no requirement to strictly start with one side and end up with the other. It's perfectly valid, and sometimes easier, to develop both sides until they meet.
I got the right answer, thanks for the help guys

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