Let ABCD be a rhombus such that its diagonals AC and BD intersects at O
Since,
The diagonals of a rhombus intersect at right angle
Therefore,
∠ACB = ∠BOC = ∠COD = ∠DOA = 90°
Now,
∠AOB = 90° = circle described on AB as diameter will pass through O
Similarly,
All the circles described on BC, AD and CD as diameter pass through O.