∫ The diameter of the circular iron sheet is 1.

The circumference of a circular iron sheet is π.

The central angle of sector ABC is 120.

∴ The arc length of the sector = 65438+ 0/3 of the circumference of the circular iron sheet (120 is 0/3 of 65438+360).

The arc length of the remaining fan-shaped iron sheet is π-π/3 = 2π/3.

∫ The bottom circumference of the cone surrounded by the left sector iron sheet = the arc length of the left sector iron sheet.

∴ Let the radius of the cone bottom be r,

Then it is: 2πR = 2π/3.

∴R = 1/3

That is, the radius of the cone bottom is 1/3.

Good luck with your study!