Question

Luas ΔABE = 4 cm²
Luas ΔFCE = 3 cm²
Luas ΔADF = 5 cm²

Dit Luas ΔAEF ?

Answer 1

Gw pake cara panjang nih:
AB = X
BC = y

x.BE = 8
y.DF = 10
(x-DF)(y-BE) = 6
xy-x.BE-y.DF+DF.BE = 6
         xy-8-10+DF.BE = 6
          xy -24 +DF.BE = 0   ; DF.BE = 80/xy
        (xy)² - 24xy +80 = 0
          (xy - 20)(xy -4) = 0

xy = 4 (ga mungkiiin, jangan tanya kenapa?)
xy = 20

maka AEF = 20 - 4 - 5 - 3
                  = 8 cm²