投とう影えい線せん

noun

projection line

Technical term used in geometry, drafting, or optics to refer to a line along which a point or object is projected.

• 図ず面めん上じょうで投とう影えい線せんを引ひいて、立りっ体たいの形けい状じょうを平へい面めんに表あらわす。

  Draw projection lines on the drawing to represent the three-dimensional shape on a plane.