If the radius ratio of three concentric circles is 1:2:3, what is the ratio of shadow area to blank area? This painting is not very standard.
Let the radius of the small circle be 1.
The radius of the middle circle is 2.
The radius of the great circle is 3.
1π+3π:2π
1+3π:2π
4π:2π
4:2
2: 1