d apres le theoreme de thales ca/cf = cb/cg =ab/fg ca/cf = ab/fg => ca =( ab x cf ) : fg ca = (3 x 8,4):11,2 ca = 2,25 cm
2. d apres la reciproque du theoreme de thales si d€[fc]et e €[fg] et si : fd/fc=fe/fg=de/cg alors (gc)//(ed) verifions! fd/fc=fe/fg => fd x fg = fc x fe fd x fg = 6,3 x 11,2 = 70,56cm fc x fe = 8,4 x 8,4 = 70,56cm donc (gc)//(ed)
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d apres le theoreme de thales
ca/cf = cb/cg =ab/fg
ca/cf = ab/fg => ca =( ab x cf ) : fg
ca = (3 x 8,4):11,2
ca = 2,25 cm
2. d apres la reciproque du theoreme de thales si d€[fc]et e €[fg] et si :
fd/fc=fe/fg=de/cg alors (gc)//(ed)
verifions!
fd/fc=fe/fg => fd x fg = fc x fe
fd x fg = 6,3 x 11,2 = 70,56cm
fc x fe = 8,4 x 8,4 = 70,56cm
donc (gc)//(ed)