Matematika

Pertanyaan

Panjang diagonal persegi panjang adalah (5x + 4) cm dan (6x - 1) cm. Jika ukuran panjang (5x - 4) cm dan lebarnya (4x) cm, maka keliling lingkaran tersebut adalah?

A. 70 cm
B. 82 cm
C. 98 cm
D. 100 cm

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2 Jawaban

  • 5x + 4 = 6x - 1
    5x - 6x = -1 - 4
    -x = -5
    x = 5

    p = 5x - 4
    p = 5.5 - 4
    p = 25 - 4
    p = 21 cm

    l = 4x
    l = 4.5
    l = 20 cm

    k = 2(p + l)
    k = 2 (21 + 20)
    k = 2 x 41
    k = 82 cm
  • diagonal 1 = diagonal 2
    5x + 4 = 6x - 1
    5x - 6x = - 4 - 1
    - x = - 5
    x = 5

    Keliling :
    = 2p + 2l
    = 2(5x - 4) + 2(4x)
    = 10x - 8 + 8x
    = 18x - 8
    = 18. 5 - 8 (masukkan nilai x = 5)
    = 90 - 8
    = 82 cm (B) 

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