Question

Diketahui luas belah ketupat 600cm.Jika panjang diagonal-diagonalnya berbanding 4 : 3, maka keliling belah ketupat tersebut adalah....

Answer 1

D₁ = 4a
d₂ = 3a
 L = 600 cm²

Luas = 1/2 x d₁ x d₂
  600 = 1/2 x 4a x 3a
  600 = 1/2 x 12a²
 12a² = 600 x 2
 12a² = 1200
     a² = 1200/12
     a² = 100
      a = √100
      a = 10 cm

d₁ = 4a = 4(10) = 40
d₂ = 3a = 3(10) = 30

S₁ = √20² + 15²
S₁ = √400 + 225
S₁ = √625
S₁ = 25 cm

Keliling = 4S₁
           = 4(25)
           = 100 cm

Answer 2

L = d1 x d2 /2
600 = 4a x 3a / 2
600 x 2 = 12a²
1200 = 12a²
a² = 100
a = 10
d1 = 4a = 40
d2 = 3a = 30

s² = 20² + 15²
s² = 400 + 225
   = 625
s = 25
K = 4 s
   = 25 x 4 = 100 cm