扇状

1. Origins, structure, and basic meaning

• Structure: 扇状 is read as せんじょう and describes a fan shape that widens outward from a narrower side like an opened folding fan.
• Basic usage: A spreading pattern appears in 扇状に広がる, while the shape of paper appears in 扇状の紙.

2. Common pitfalls and similar expressions

• Adverbial and modifying forms
  • Use 扇状に for the shape of an action and 扇状の before a noun.
• Difference from 円形
  • 円形 is a round circular shape, while 扇状 is narrow on one side and widens toward the other like a fan.