Yes, you may ask that and it is a darn good question. I wanted to keep it clean until you were ready. It is now open for business.

]]> "Of all the triangles possible within a givin perimeter, the equilateral triangle has the largest possible area"

What is this property called?

Am I allowed to call it "The Isoperimetric Property of an Equilateral Triangle"

]]>According to which book?

But he couldn't solve it for 3 variables]]>

It is a little easier to understand with a trivial example:

Prove, with a,b>=0;

Square both sides:

The boxed term is positive!

]]>Thank You

I think my Father told me this but I forgot]]>

Look at the RHS. The first term is now clearly positive.

The second term is also positive because each term is squared.

Multiplying two positive numbers yields a positive number so we have:

]]>I would be very happy to see it explained]]>

What is wrong?

The first line is from the problem itself. The second line is known to inequality provers. You can not even get it with a package! It is derived from this relationship:

Before we go further do you understand why the proof works? It is a very important concept in these type of proofs.

Would you like to see some more proofs of this?

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