Matematika

Pertanyaan

31. Pada gambar di atas, panjang AD =....

32. Pada gambar di atas, panjang EF =....
31. Pada gambar di atas, panjang AD =.... 32. Pada gambar di atas, panjang EF =....

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  • 31)
    CF = 6 cm
    FB = 14 cm
    EF = DB = 8 cm

    CF/(CF+FB) = EF/(AD+DB)
    6/(6+14) = 8/(AD+8)
    6/20 = 8/(AD+8)
    6 × (AD + 8) = 8 × 20
    6AD + 48 = 160
    6AD = 160 - 48
    6AD = 112
    AD = 112/6
    AD = 18 4/6
    AD = 18 2/3 cm (C)

    32)
    DE = 3 cm
    EA = 7 cm
    DC = 8 cm
    AB = 14 cm

    DE/(DE+EA) = (EF-8)/(AB-8)
    3/(3+7) = (EF-8)/(14-8)
    3/10 = (EF-8)/6
    3 × 6 = (EF-8) × 10
    18 = 10EF - 80
    10EF = 18 + 80
    10EF = 98
    EF = 98/10
    EF = 9,8 cm (B)

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