If I draw a 3d equal sided cube on a flat piece of paper, and I measure each line on the paper, I will get a different length on the diagnals than I will on the verticles and horizontals. But thats because I'm measuring in 2d.
I know in my mind that the cube is equal sided in length...but since the paper i drew it on is 2d, the measurement comes out different then if I measured it on a 3d cube.
Now consider the diameter of a circle...it exists in 1d
Yet the perimeter is being measured in 2d! Yet we make no correction mathmatically for the change in dimension when trying to divide the 2d diameter into the 2d perimeter!
That's why Pi never solves to a perfect number...we are calculating it wrong!
To compare apples to apples...you have to envision that you are looking at the diameter like the thin edge of a dime. in 1 or 2d it looks like a line, but flip it to a side and you see that it is actually a curved half circle...
And since a half cirlce fits into a full circle twice...then pi = 2!
You must apply all lines to the same dimensionality before getting a proper calculation...just like you must do to the lines of the cube on the 2d paper if you want to get an accurate result.