Question

why a two adjoining angles are 180o​

Answer 1

A linear pair is two adjacent angles that have a sum of 180 degrees, as a result, they form a line. You can have two angles that are supplementary, but not adjacent, so they are not a linear pair, instead, they will just be supplementary.

Answer 2

Answer:

Two angles are said to be supplementary such that the sum of the two angles is 180 degrees. For e.g if there are two angles : 120 degree and 60 degree each, then these angles are supplementary because the sum of these angles : 120 + 60 = 180 degrees.