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**Debanjan****Member**- Registered: 2013-11-13
- Posts: 4

let there be two sets A and B.

IF A=B then is A union B = A intersection B ??

I would love to know your logic behind the same.

Note : A and B can be any two types of sets.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 84,766

Hi Debanjan;

If the two sets are equal then the union of them is the set itself and the intersection of them is the set itself so the answer is yes.

**In mathematics, you don't understand things. You just get used to them.I have the result, but I do not yet know how to get it.All physicists, and a good many quite respectable mathematicians are contemptuous about proof.**

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**rahat****Member**- Registered: 2013-12-15
- Posts: 1

very difficult

i am no mathematician

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 84,766

Hi rahat;

What do you not understand?

**In mathematics, you don't understand things. You just get used to them.I have the result, but I do not yet know how to get it.All physicists, and a good many quite respectable mathematicians are contemptuous about proof.**

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,317

hi rahat,

Welcome to the forum.

A picture speaks a thousand words. See below (click to make bigger).

The blue region is A intersect B.

The union is all in both circles.

Now what happens if you slide one circle so it coincides with the other?

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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