Symmetric set

Nickfytas

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Sep 12, 2019
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Suppose we have a bounded and connected subset D of R^2 and it is symmetric with respect to the x-axis
Is it true that D1=D2 and why.
Where D1={(x,y)eD : y>=0} and D2={(x,y)eD : y<0}
 
I would not say "D1= D2". We reserve "=" to mean they are the same thing which is not the case. it is true that D1 and D2 have the same area, the same "shape", etc..
 
I would not say "D1= D2". We reserve "=" to mean they are the same thing which is not the case. it is true that D1 and D2 have the same area, the same "shape", etc..
I want to prove that the integral in D is 2 times the integral in the D1 and I can’t it prove without saying D1=D2
 
No, you want to say that the integral in D1 and the integral in D2 are the same number, NOT that D1 and D2 are the same set!
 
I want to prove that the integral in D is 2 times the integral in the D1 and I can’t it prove without saying D1=D2
You need to show your work - so that we know where to begin to help you.

You have not shown any work - you have just stated what you don't want to do.

What does symmetry in sets mean to you?
 
I see .
So far I have done this . But I want to prove it using integral algebra not just words
 

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