Complementary, supplementary and adjacent angles

We can say that a angle is the region of the plane limited by two semi-straight of the same origin. Watch:

complementary angles

anglescomplementary they are two angles whose sum results in 90º, that is, one is the complement of the other.

Angles whose sum equals 90°
Angles whose sum equals 90°

In the illustration, we have to:

α + β = 90º

α = 90º – β

β = 90º – α

supplementary angles

anglessupplementary they are two angles that, added together, are equal to 180º, thus, one is the supplement of the other.

Angles whose sum equals 180°
Angles whose sum equals 180°

In the illustration, we have to:

α + β = 180º

α = 180º – β

β = 180º – α

adjacent angles

anglesadjacent are those that have one side in common, but the given regions have no common points. Note the illustration:

Angles that have sides in common
Angles that have sides in common

Angles AÔB and BÔC are adjacent, because they have the OB side in common, but their determined regions do not have points in common.

Angles AÔC and AÔB are not adjacent, although they have one side in common, as their particular regions have points in common. Region AÔB belongs to region AÔC.

Adjacent and supplementary angles

According to the illustration above, angles AÔB and BÔC are adjacent, as they have the OB side in common and their determined areas do not have double points. They are also supplementary, since the sum of angles α and β totals 180º.

by Mark Noah
Graduated in Mathematics

Source: Brazil School - https://brasilescola.uol.com.br/matematica/angulos-complementares-angulos-suplementares-angulos-.htm

Encceja test takes place on August 28

On August 28, 2022, the National Examination for the Certification of Youth and Adult Skills will...

read more

Income Tax: what it is, who should declare it and how to do it

Every year citizens and businesses are required to declare the Income tax, but still there are ma...

read more

In the comfort of home: learn how to declare the IR 2023 with your cell phone

The period for filing the Income Tax (IR) began last Wednesday, March 15th, and runs until May 31...

read more