Make a square with each side (square root of 2) times the cicrcle's radius (1/2 the diameter) and the square exactly fits inside the circle.
You draw 2 diameters through the center of the circle. The 2 diameters must be perpendicular. The vertexes of the square are the 4 points where the diameters meet the circles. ;
To inscribe a square in a circle, first draw a circle and mark its center. Then draw perpendicular diameters to find the square's corners and connect them to form the square, which will touch the circle at each corner. The sides of the square will measure r 2 where r is the circle's radius.
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