Question

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Answer 1

Answer:

construction :- drawn a line parallel to PQ as well as ST whose name is AB

proof:-ST || AB(by constructionl

angle TSR=angle SRA(alt. int. angle)

then angle SRA=140°------eq.(i)

PQ||AB (by construction)

angle PQR=angle QRB(alt.int.angle)

then angle QRB=120°------eq.(ii)

so, angleQRS=angleSRA-angleQRB

angle QRS=140-120{from(i) and (ii)

so, angle QRS=20°