If two diameters of a circle intersect each other at right angles, then quadrilateral formed by joining their end points is a
Let AB and CD are two diameters of circle
∠AOD = ∠BOD = ∠BOC = ∠AOC = 90°
AB and CD are diagonals of quadrilateral ABCD
They intersect each other at right angles
And
AB = BC = CD = DA
We know that,
Sides of a square are equal and diagonals intersect at 90°
Therefore, ABCD is a square