reflex angle
- noun
- /ˈrɪflɛks ˈæŋɡəl/
- Specialized
:
ángulo reflexo
- A reflex angle is formed when the rotation of a ray exceeds 180 degrees but is less than 360 degrees.
Examples
-
A reflex angle can be found by subtracting the given angle from 360 degrees.
-
When you open a book so the covers form a reflex angle, it is nearly flat.
-
The exterior angle of a regular pentagon is a reflex angle.
-
A reflex angle measures more than 180 degrees.
-
Is a reflex angle always greater than a straight angle?
-
To create a reflex angle, extend one side of a straight angle beyond the straight line.
-
In geometry class, we learned that any angle measuring between 180 degrees and 360 degrees is classified as a reflex angle.
Synonyms
An inside corner of a shape that points inward more than a straight line
An inside corner of a shape that bends inward past a straight line
How Large
- Specialized
- Specialized
- Specialized
1
3.4
- Specialized
16
2.4
- Specialized
1
2.8
Surface Forms
Morphology
reflex + angle
The noun 'angle' is transparent, and 'reflex' (etymologically ‘bent back’) gives a clue that the angle is beyond a straight line, so there's a partial compositional link to an angle >180°. However, the precise numeric range (more than 180° but less than 360°) and the technical geometric sense of 'reflex' are specialized and not reliably predictable by an average B1 learner, making this only partially transparent.
Etymology
Reflex angle comes from the idea of reflex meaning 'bending back' and angle as the turn between two lines, so imagine an arm or a book bent back past a straight line. So, a reflex angle is a turn that goes past a straight line and is 'more than 180 degrees', which is why the name fits its meaning.