The rhombus here is a square. As the rhombus is cyclic, cum of opposite angles is 180 degree, which are equal. So, each angle is 90 degree and the rhombus is a square.
Area of circle = 2826 cm^2
pi*r^2=2826 (let the radius of circle be r)
r=30 cm
Each diagonal = 2r
Area of square = 1/2 (D)^2
solve
ans 1800 cm^2
option 5