supplementary angles

Meaning

1. 1nounpluralmathematicstechnical

   Two angles whose sizes add up to exactly 180 degrees, so that together they form a straight line.

   Grammar: Plural: supplementary angles are always a pair. For one angle you say it is the supplement of another.

   Patterns

   • supplementary angles of something
   • angles that are supplementary

   An angle of 110 degrees and one of 70 degrees are supplementary angles.

   When two lines cross, the neighboring angles are supplementary angles.

   If one of two supplementary angles is acute, the other must be obtuse.

Common combinations

a pair of supplementary angles

Each pair of supplementary angles in the diagram adds up to 180 degrees.

find the supplementary angle

To find the supplementary angle, subtract from 180.

supplementary angles add up to

Supplementary angles add up to 180 degrees.

linear pair

A linear pair is a set of supplementary angles that share a side.

adjacent supplementary angles

Adjacent supplementary angles lie side by side on a straight line.

Synonyms and how they differ

supplement

In geometry, a supplement is one angle of the pair, whereas supplementary angles names the two together.

linear pair

A linear pair is a special case where the two supplementary angles sit next to each other along a line.

Word family

supplement noun

something added, or in geometry, the angle that adds to another to make 180 degrees

supplementary adjective

added as an extra, or making 180 degrees with another angle

complementary angles noun

two angles that together make 90 degrees

angle noun

the amount of turn between two lines that meet

Commonly confused: supplementary angles or complementary angles?

Practice

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