A rotation is a rigid transformation, this means that the shape changes location but does not change its size. So even if triangle PQR was rotated to P'Q'R', the side lengths remain the same so that
PQ=P'Q'= 9
QR=Q'R'= 12
RP=R'P'= 7
The same happens with the angles
Q=∠Q'=35°
R=∠R'=48|°
180-()35+48= 97°
So
P'Q'=9
P'=97|°
