As the sum of the angles forming a linear pair is.
As the statement is incomplete in itself.
Let us assume one of the angle in a linear pair be; such that ,that is, an acute angle.
Therefore, the other angle in the linear pair becomes, which clearly cannot be acute.
Let one of the angle in the linear pair be. Then, other angle also becomes equal to.
Therefore, by the definition of linear pair, we get:
Hence, if angles forming a linear pair are equal, then each of these angles is of measure.