Opposite sides and opposite angles in a parallelogram are congruent. $\displaystyle\angle{S}\usepackage{cmbright}\Huge\$ and $\displaystyle\angle{Q}\usepackage{cmbright}\Huge\$ are opposite angles and are congruent. However, because $\displaystyle{\overline{{{R}{S}}}}\usepackage{cmbright}\Huge\$ and $\displaystyle{\overline{{{S}{T}}}}\usepackage{cmbright}\Huge\$ are adjacent sides in parallelogram RSTQ, they are not necessarily congruent.