平角(へいかく)

へいかく
noun
straight angle; 180-degree angle
1. straight angle; angle of 180 degrees
An angle of 180 degrees, formed by two rays pointing in exactly opposite directions so that they make a straight line.
平角(へいかく)は180度(ど)だ。
A straight angle is 180 degrees.
直角(ちょっかく)を二(ふた)つ合(あ)わせると平角(へいかく)になる。
Two right angles together make a straight angle.
一直線(いっちょくせん)に並(なら)んだ二(ふた)つの半直線(はんちょくせん)がつくる角(かく)を平角(へいかく)という。
The angle formed by two rays lying in a straight line is called a straight angle.

Composed of 平(へい) (flat, level) + 角(かく) (angle). A mathematics term for an angle of exactly 180 degrees.

RELATED TERMS:

  • 直角(ちょっかく): right angle — 90 degrees
  • 鋭角(えいかく): acute angle — less than 90 degrees
  • 鈍角(どんかく): obtuse angle — between 90 and 180 degrees
general
Added 2026.5.18 12:04
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