Answer: side length=12([tex]\sqrt{2}+1[/tex]) cm
Step-by-step explanation:
l=length of side.
12+l=[tex]\sqrt{2l^{2} }[/tex]
(12+l)/l=[tex]\sqrt{2}[/tex]
12/l+1=[tex]\sqrt{2}[/tex]
12/l=[tex]\sqrt{2}[/tex]-1
l/12=1/([tex]\sqrt{2} -1[/tex])
l=12/([tex]\sqrt{2}-1[/tex])
l=12([tex]\sqrt{2}+1[/tex])/[tex](\sqrt{2} +1)(\sqrt{2} -1)[/tex]
l=12([tex]\sqrt{2}+1[/tex])/(2-1)
l=12([tex]\sqrt{2}+1[/tex]) cm