Draw a circle and any two …

A circle can be drawn of any convenient radius, also having its centre as O. Let AB and CD be two diameters of this circle. When we join the ends of these diameters, a quadrilateral ABCD is formed.
As we know that the diameters of a circle are equal in length, therefore, the quadrilateral so formed will have its diagonals of equal length.
Also, OA=OB=OC=OD radius r and if a quadrilateral has its diagonals of same length which are bisecting each other, then it will be a rectangle.
Let DE and FG be two diameters of this circle such that these are perpendicular to each other. A quadrilateral is formed by joining the ends of these diameters.
Here, OD=OE=OF=OG=radius r
In this quadrilateral DEFG, the diagonals are equal and perpendicular to each other.
Also, since these are bisecting each other, it will be a square. The length of these sides of the quadrilateral so formed can be measured to check our answers.