Question 1202123
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Note that SQ is shown with a break, but then it would not be a line, so one must assume SQ is a single straight line.

Draw line ST.  Now you have triangles STQ and RTS.   For these two triangles you have  RS = QT and RT = SQ (both given) AND ST = ST.   So by SSS (side-side-side), you have  triangle STQ congruent to triangle RTS.  For congruent triangles, corresponding angles are equal.