半はん直ちょく線せん

noun

half line; ray

Mathematical term for a line that starts at a point and extends infinitely in one direction.

• 半はん直ちょく線せんは、一いっ点てんから始はじまり、一いち方ほう向こうに無む限げんに伸のびる。

  A ray starts from a point and extends infinitely in one direction.