半径(はんけい)

はんけい
noun
radius
1. radius
The distance from the center of a circle to its edge; also used to describe the area within a certain distance from a point.
円(えん)の半径(はんけい)は5センチです。
The radius of the circle is 5 centimeters.
駅(えき)から半径(はんけい)1キロ以内(いない)にコンビニがある。
There's a convenience store within a 1 km radius of the station.
車(くるま)を買(か)ってから行動(こうどう)半径(はんけい)が広(ひろ)がった。
Since buying a car, my range of activities has expanded.

USAGE: 半径(はんけい) is used both in mathematics (geometry) and in everyday contexts to describe the area within a certain distance from a center point.

COMMON PATTERNS:

  • 半径(はんけい)X{メートル/キロ} (radius of X meters/km)
  • 半径(はんけい)X以内(いない) (within a radius of X)
  • 行動(こうどう)半径(はんけい) (range of activities)

MATHEMATICS:

  • 半径(はんけい) - radius (r)
  • 直径(ちょっけい) - diameter
  • 円周(えんしゅう) - circumference

NOTE: 行動(こうどう)半径(はんけい) (action radius) is a common figurative usage meaning the scope or range of one's activities.

general
Added 2026.1.14 9:58 · Revised 2026.3.4 12:07
04000/04331_hankei