Answer :

AL2006
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.

Answer:

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.

Step-by-step explanation: