The angles in a linear pair are_________.

• Linear pair is a pair of adjacent angles whose non-common arms are opposite rays.
• A linear pair forms a straight angle that measures 180^o.
• So we have 2 angles whose measures add up to 180^o, which means they are supplementary.                   
• For example, In the figure, we can see $\angle \mathrm{AOC}$ and $\angle \mathrm{BOC}$  are adjacent to each other after the intersection of two lines.
• So, $\angle \mathrm{AOC}$ and $\angle \mathrm{BOC}$ form a linear pair. 
• From the figure, we can say that the sum of $\angle \mathrm{AOC}$ and $\angle \mathrm{BOC}$ is equal to the sum of $\angle \mathrm{AOB}$. 
• Since $\angle \mathrm{AOB}$ is an angle on a line AB and hence, it is a straight angle. Therefore, $\angle \mathrm{AOB}$ =180^∘
• As we can see, the sum of $\angle \mathrm{AOC}$ and $\angle \mathrm{BOC}$ is 180^o which means these are supplementary angles. They were linear pairs of angles, so we can say that angles forming a linear pair are supplementary.

.