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# Region bounded by sinh watch

1. Hi all,
I can't seem to get the correct answer to this question- help please!!
The region R in the x-y plane is bounded by y=sinhx, the x-axis and the line AB which is perpendicular to the x-axis.
Given that AB=0.75, show that OB=ln3.

So I put y=0.75 into y=sinhx and rearrange to get arcsinh0.75=x
Then I use the logarithmic form to solve and get ln2… I must be doing something stupid: can somebody please tell me what!?!?

Regards,
Bently7
2. (Original post by Bently7)
Hi all,
I can't seem to get the correct answer to this question- help please!!
The region R in the x-y plane is bounded by y=sinhx, the x-axis and the line AB which is perpendicular to the x-axis.
Given that AB=0.75, show that OB=ln3.

So I put y=0.75 into y=sinhx and rearrange to get arcsinh0.75=x
Then I use the logarithmic form to solve and get ln2… I must be doing something stupid: can somebody please tell me what!?!?

Regards,
Bently7
If B's on the x-axis, then ln2 seems correct. If you sub ln2 back into the defn of y you get 3/4.

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Updated: April 13, 2011
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