no 40 please pake jalan

DE

AC/AE = BC/DE
4/12 = 5/DE
4DE = 60
DE = 15 cm

AB

AB/AD = BC/DE
AB/(AB+6) = 5/15
15AB = 5(AB+6)
15AB = 5AB + 30
15AB - 5AB = 30
10AB = 30
AB = 3 cm


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