Yes that is correct MathsGod 
ok so square root 'undoes' square!
$$\sqrt{9^2}=\sqrt{81}=9$$
If the length of the square is $$9 cm$$ then the area will be $$9^2cm^2=81cm^2$$
If the area of the square is $$81cm^2$$ then the length will be $$\sqrt{81}cm = 9cm$$
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NOW
I went to a lot of trouble to draw that diagram.
So can you answer the questions at the bottom please? I am trying to make sure that you understand an important concept here.
Did you go through the maths is fun page that I sent you to?
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When you get sick of my questions then you can just say you have had enough for now
OR you can just stop answering.
Either way you can start again when and if you want to.
I like teaching you but I honestly will not mind.