1) [tex]\overline{RS} \perp \overline{ST}, \overline{RS} \perp \overline{SQ}, \angle STR \cong \angle SQR[/tex] (given)
2) [tex]\overline{RS} \cong \overline{RS}[/tex] (reflexive property)
3) [tex]\angle RST[/tex] and [tex]\angle RSQ[/tex] are right angles (perpendicular lines form right angles)
4) [tex]\triangle RST \cong \triangle RSQ[/tex] (AAS)