From the figure we notice that the triangle is an isosceles one. This means that the angles RTS and RST are the same. Hence:
[tex]m\angle RTS=m\angle RST=71[/tex]To find the remaining angle we need to use the fact that the sum of the interior angles of any triangle is 180, then:
[tex]m\angle TRS+m\angle RTS+m\angle RST=180[/tex]Plugging the values we know and solving for TRS we have:
[tex]\begin{gathered} m\angle TRS+71+71=180 \\ m\angle TRS=180-71-71 \\ m\angle TRS=38 \end{gathered}[/tex]Therefore, the angle TRS is 38°.