question_answer 24)

                Find \[m\angle C\] in the figure, if \[\overline{AB}||\overline{DC}\]

Answer:

                \[\because \,\,\,\,\,\,\,AB||DC\] \[\therefore \]  \[m\angle C+m\angle B={{180}^{\text{o}}}\] | i.e., the sum of interior opposite angles is \[{{180}^{\text{o}}}\]. \[\Rightarrow \]               \[m\angle C+{{120}^{\text{o}}}={{180}^{\text{o}}}\] \[\Rightarrow \]               \[m\angle C={{180}^{\text{o}}}-{{120}^{\text{o}}}={{60}^{\text{o}}}\].