[tex]\textsf {21 cm}[/tex]
[tex]\textsf {If it is correct to the nearest centimeter, then the least side length}\\\textsf {would be 8 - 1 = 7 cm. }[/tex]
[tex]\textsf {Then, the least possible perimeter would be :}[/tex]
[tex]\mathsf {7 \times 3}[/tex]
[tex]\textsf {21 cm}[/tex]
