Diketahui panjang salah satu diagonal belah ketupat 48 cm.Jika keliling belah ketupat 100 cm, maka luas belah ketupat adalah? A. 84 cm² B. 168 cm² C. 336 cm² D.

dik :
d₁ = 48 cm
k = 100 cm

dit : L = ?

jawab :
1/2 d₂ = [tex] \sqrt{(100/4)²-(48/2)²} = \sqrt{25²-24²} = \sqrt{625-576} = \sqrt{49} = 7 [/tex]
d₂ = 2 × 7 = 14 cm
L = 1/2 × d₁ × d₂ = 1/2 × 48 × 14 = 336 cm²

(C. 336 cm²)

d1 = 48 cm
keliling = 100 cm

Keliling = 4 × s
100 = 4 × s
s = 100/4
s = 25 cm

d2 = 2 × √(s² - d1/2²)
d2 = 2 × √(25² - 48/2²)
d2 = 2 × √(625 - 24²)
d2 = 2 × √(625 - 576)
d2 = 2 × √49
d2 = 2 × 7 = 14 cm

Luas = 1/2 × d1 × d2
= 1/2 × 48 × 14
= 1/2 × 672
= 336 cm²

Opsi C