Why we put m sign in demonstrative geometry in theorem?
please tell me while proving theorems
in statements why there is m symbol before angles like m<ABC + m<BCD=180
To add, when we take a sum of two angles, we must use to convert angles as figures to numbers first and then to add the results. That's why is used in . To say that two angles are congruent, we don't need since we could say . The latter fact is equivalent to .