The angles whose sum equals to $180^\circ$ are called the supplementary angles.

Supplementary angles are basically two angles but the sum of them represents a straight angle when the angles are added to each other.

One angle is known as supplement of another angle and vice-versa.

$\alpha$ and $\beta$ are two angles and the sum of them forms a straight angle geometrically.

$\alpha+\beta = 180^\circ$

- $\alpha$ is called as supplement of $\beta$
- $\beta$ is called as supplement of $\alpha$

The two angles $\alpha$ and $\beta$ are known as supplementary angles.

$\Delta PQR$ is a triangle and the side $\overline{RS}$ splits this triangle as two triangles $\Delta PSR$ and $\Delta QSR$.

Measures $\angle PSR$ and $\angle QSR$ by using protractor.

It is measured that the $\angle PSR$ is equal to $48^\circ$ and the $\angle QSR$ is equal to $132^\circ$. Now, add both angles to get sum of them.

$\angle PSR + \angle QSR$ $=$ $48^° + 132^°$

$\implies$ $\angle PSR + \angle QSR$ $=$ $180^°$

The sum of the two angles is straight angle ${(\pi)}$. Therefore, the angles ($\angle PSR$ and $\angle QSR$) are called as supplementary angles.

The $\angle PSR$ is called as supplement of the $\angle QSR$. Similarly, $\angle QSR$ is called as supplement of the $\angle PSR$.

Math Doubts is a best place to learn mathematics and from basics to advanced scientific level for students, teachers and researchers.
Know more

Learn how to solve easy to difficult mathematics problems of all topics in various methods with step by step process and also maths questions for practising.