Textbook Problem

Which of the following statements would you prove by the indirect method?

a) In triangle $ABC$, if $\text{m}\angle A>\text{m}\angle B$, then $AC\ne BC$.

b) If alternate exterior $\angle 1\cancel{\cong }$ alternate exterior $\angle 8$, then $\mathcal{l}$ is not parallel to $m$.

c) If $\left(x+2\right)\cdot \left(x-3\right)=0$, then $x=-2\text{or}x=3$.

d) If two sides of a triangle are congruent, the two angles opposite these sides are also congruent.

e) The perpendicular bisector of a line segment is unique.