Answer:
840
Step-by-step explanation:
Hi there!
Usually, this kind of problem asks us the perimeter rather than the area. But when talking on this grid on how many cms are necessary to construct one made up of 9 squares 1cm x1 cm. We need to check one thing: Some line segments will be used twice. So this is not a classical perimeter question.
1) So we either manually and carefully count it avoiding not doing it twice the same common line segments.
Or.
2) By just applying an algorithm, Where n is the nxn grid
[tex]n(n+1)+n(n+1)=Length \:of \:the \:wire[/tex]
So, for the 20x20 grid
[tex]20(20+1)+20(20+1)=length\\\\20(21)+20(21)=length\\length=840 cm[/tex]
