Let ABCD be a square of side 2m. We form a regular octagon by cutting all four corners.
Let EF=FG=GH=HI=IJ=JK=KL=LE=x
By symmetry, AE=AL=BG=BF=CH=CI=DJ=DK=a
Using Pythagoras theorem in △ALE, we get
LE2=AL2+AE2
x2=a2+a2=2a2⇒x=√2a
And AB=AE+EF+FB⇒2=a+x+a→2a+x=2
Put the value of x, we get
2a+√2a=2⇒a√2(√2+1)=2⇒a=√2√2+1
∴x=√2.√2√2+1=2√2+1
∴Length of each side of the octagon is 2√2+1m