tolong jawab pake cara ya kak, makasih

AB = 3/5 BC
AC = 4/5 BC

K = AB+BC+AC
18 = 3/5 BC + BC + 4/5 BC
18 = 12/5 BC
BC = 7,5 cm

AB = 3/5 BC = 4,5 cm
AC = 4/5 BC = 6 cm

L = 0,5·AB·AC
   = 0,5·4,5·6
   = 13,5 cm²   (B)


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