Answer
a. The common side is $\overline{ad}$
b. The common side is $\overline{ab}$
Work Step by Step
a. $\triangle$ ABD and $\triangle$ DCA both share the bottom side, which is $\overline{ad}$
b. $\triangle$ ABD and $\triangle$ BAC both share the left side, which is $\overline{ab}$
