We rotate the shape counterclockwise by the amount indicated and see where the point or segment in question ends up.
A 90° maps to H
B 180° maps to G
G 270° maps to I
AB 90° maps to HI
FO 180° maps to AO
GF 270° maps to IH
DG 90° maps to BD
AH 90° maps to HF
BO 270° maps to DO
