Réponse:

EG/EI=EF/EH=GF/IH

EI=EG+GI EI=13+10 ,4 EI=23,4cm

EH=EF+FH EH=25+20 EH=45cm

13/23,4=25/45=GF/54

13/23,4=GF/54 25/45=GF/54

(13×54)/23,4=30 (25×54)/45=30

GF=30 cm