they're all different depending on the size of your circle/sphere buddy :]
Radii is a brand of sports footwear.
There are infinite radii in a sphere.
The plural of radius is radii.
2 radii = one diameter
the single form of radii is radius
A hydrogen atom has the smallest radii.
These three radii are of different lengths.
It is radii which is the plural of radius
The covalent radii is for atoms.
The noun radii is already a plural. The singular is radius.
The word radii has 3 syllables. They are: ra di i
Classically, the plural should be radii, (usually pronounced ray-dee-eye) because 'radius' is a Latin word.However, in modern English, radiuses is acceptable.