鋭角(えいかく)

鋭角(えいかく) is a mathematical term for an angle less than 90 degrees. The kanji 鋭(えい) means 'sharp,' reflecting the pointed appearance of small angles.

ANGLE TYPES:

• 鋭角(えいかく): acute angle (0° < θ < 90°)
• 直角(ちょっかく): right angle (θ = 90°)
• 鈍角(どんかく): obtuse angle (90° < θ < 180°)
• 平角(へいかく): straight angle (θ = 180°)

RELATED TERMS:

• 鋭角(えいかく)三角形(さんかくけい): acute triangle (all angles acute)
• 角度(かくど): angle (measurement)
• 三角形(さんかくけい): triangle

FIGURATIVE USE:
鋭角(えいかく)的(てき) (adjective) can describe something sharp or incisive, as in 鋭角(えいかく)的(てき)な視点(してん) (a sharp perspective).