Strange but true
The centre circle and the arc on the penalty area have the same radius: 9.15 m.
Both markings are drawn 9.15 m out — one from the centre mark, one from the penalty mark.
Standard-defined
Why this is interesting
Two markings at opposite ends of the pitch are the same curve.
How this measurement works
Law 1 of the Laws of the Game sets the radius of the centre circle at 9.15 m. The arc at the top of each penalty area is also drawn with a 9.15 m radius, measured from the penalty mark.
How certain is this?
Standard-defined — specified by the Laws of the Game.
Sources & further reading
International Football Association Board
Laws of the Game(opens external site)
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