Because circle all have the same proportions. You can take any circle, and just evenly make it bigger or smaller to make it perfectly overlap with any other circle.
The ratios of shapes only ever change if their proportions change. That’s why every single square also always has the same ratio between it’s side and diagonal (√2).
And the ratio of a rectangles side to it’s diagonal will always be the same, regardless of size, as long as the aspect ratio is the same.
That’s literally what a ratio of a shape lengths are supposed to measure: if you scale two shapes of equal ratios to the same size, they will always be identical, because that’s what ratios are defined to tell you.
And since any circle is completely indistinguishable from any other circle, except for size, all ratios of a circles size will always be identical
Because circle all have the same proportions. You can take any circle, and just evenly make it bigger or smaller to make it perfectly overlap with any other circle.
The ratios of shapes only ever change if their proportions change. That’s why every single square also always has the same ratio between it’s side and diagonal (√2).
And the ratio of a rectangles side to it’s diagonal will always be the same, regardless of size, as long as the aspect ratio is the same.
That’s literally what a ratio of a shape lengths are supposed to measure: if you scale two shapes of equal ratios to the same size, they will always be identical, because that’s what ratios are defined to tell you.
And since any circle is completely indistinguishable from any other circle, except for size, all ratios of a circles size will always be identical