How can you construct a square

The problem says construct a square with the given perimeter of p. It also has a picture of a segment.

draw line segment of given perimeter. say AB
B------------------------------A
Bisect AB (perpendicular bisector. say O
B--------------O----------------A
Bisect OB and OA (perpendicular bisector. say M and N
B-------M-------O-------N--------A
draw perpendiculars at M and O say MP and OQ
measure distance OM in compass and draw arcs on perpendiculars to cut at say P and Q
join P and Q (points on the arcs
MPQO is required square.
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you can construct x4 right angles XD