supplementary angle: meaning, definition, pronunciation and examples
C1Technical/Academic
Quick answer
What does “supplementary angle” mean?
One of two angles whose sum is 180 degrees.
Audio
Pronunciation
Definition
Meaning and Definition
One of two angles whose sum is 180 degrees.
In geometry, either of a pair of angles that, when placed adjacent to each other, form a straight line; the term is also used metaphorically to describe complementary or completing elements in a non-mathematical context.
Dialectal Variation
British vs American Usage
Differences
No significant lexical or definitional differences. Spelling follows regional norms (e.g., 'maths' vs. 'math' in surrounding text).
Connotations
Purely mathematical/technical in both varieties.
Frequency
Used with identical frequency in secondary and tertiary STEM education contexts in both regions.
Grammar
How to Use “supplementary angle” in a Sentence
Angle X is supplementary to angle Y.Angles A and B are supplementary.Find the supplementary angle.Vocabulary
Collocations
Examples
Examples of “supplementary angle” in a Sentence
adjective
British English
- The two angles are supplementary.
- We studied supplementary angle theorems in maths class.
American English
- These angles are supplementary.
- The problem involves finding supplementary angles in geometry.
Usage
Meaning in Context
Business
Virtually never used.
Academic
Core terminology in geometry, trigonometry, and engineering courses.
Everyday
Only in specific educational or DIY contexts (e.g., carpentry).
Technical
Fundamental term in mathematics, physics, architecture, and drafting.
Vocabulary
Synonyms of “supplementary angle”
Strong
Neutral
Weak
Vocabulary
Antonyms of “supplementary angle”
Watch out
Common Mistakes When Using “supplementary angle”
- Confusing 'supplementary' (180°) with 'complementary' (90°).
- Using 'supplementary' as a noun without 'angle' (e.g., 'They are supplementaries.' – incorrect).
- Misspelling as 'suplementary'.
FAQ
Frequently Asked Questions
Complementary angles sum to 90 degrees, while supplementary angles sum to 180 degrees.
Yes, the definition only requires their measures sum to 180°; they do not have to share a vertex or side.
Yes, a 90° angle is supplementary to another 90° angle (90° + 90° = 180°).
The supplementary angle of any acute angle (less than 90°) is always an obtuse angle (greater than 90°).
One of two angles whose sum is 180 degrees.
Supplementary angle is usually technical/academic in register.
Supplementary angle: in British English it is pronounced /ˌsʌplɪˈment(ə)ri ˈæŋɡl/, and in American English it is pronounced /ˌsʌpləˈmentəri ˈæŋɡl/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “They are as supplementary as two angles on a straight line. (Rare, metaphorical)”
Learning
Memory Aids
Mnemonic
Think 'SUPPLY'mentary – it SUPPLIES what's needed to reach a straight line (180°).
Conceptual Metaphor
COMPLETION IS A SUM; A PARTNER THAT MAKES A WHOLE (LINE).
Practice
Quiz
What is the supplementary angle of 37°?