鋭角三角形

鋭角 (“acute angle”) +‎ 三角形 (“triangle”)

鋭(えい)角(かく)三(さん)角(かっ)形(けい) • (eikaku sankakkei) 

1. acute triangle (triangle all of the angles of which are acute)

• 鈍角三角形(どんかくさんかっけい) (donkaku sankakkei)

• Shinmura, Izuru, editor (1998), 広辞苑 [Kōjien] (in Japanese), Fifth edition, Tokyo: Iwanami Shoten, →ISBN