Question

If the sum of two adjacent angle is 180 then the angle form a line

Answer 1

When a ray stands on a line, two adjacent angles are formed. We know that the angle lying on a straight line is 180°. The two angles being adjacent, make a total angle of 180° on the straight line.

Answer 2

yes off course it's true
if the sum of two adjacent angles is 180 then it is a line