直ちょっ角かく三さん角かっ形けい

also: ちょっかくさんかくけい

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Meanings

right triangle; right-angled triangle

A triangle with one 90-degree angle. Used in geometry contexts.

二に等とう辺へん三さん角かっ形けい
An isosceles triangle, which has two equal sides, unlike a right triangle defined by a 90-degree angle.
正せい三さん角かっ形けい
An equilateral triangle with all sides equal; a right triangle can be isosceles but not equilateral.

直角三角形
- ちょっかくさんかっけい
  Standard kanji spelling; the reading ちょっかくさんかっけい is the most common pronunciation.
- ちょっかくさんかくけい
  Alternate reading; less common but still encountered.
ちょっかくさんかくけい

Compound of 直角 (right angle) + 三角形 (triangle). The reading ちょっかくさんかっけい is a common contraction of ちょっかくさんかくけい.