A right angle is a perfect square corner of ninety degrees. The corner of a book, a brick or a window frame.
It is the foundation of nearly all building and drawing, which is why a set square and a builder's square exist to check them. Two lines meeting at a right angle are perpendicular to each other. The phrase at right angles to means crossing something squarely. A triangle containing one is a right-angled triangle, which is what the whole of trigonometry is built on.
1nounright angleAn angle of ninety degrees.
“The two walls meet at a right angle.”
Latin
angulus rectus
English, today
right angle
Latin angulus rectus.
Etymology from Wiktionary, CC BY-SA
Practised in A Man Called Ove, Light & Shadow, Shapes & Lines
First appears in chapter 5 of A Man Called Ove.
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