Diketahui panjang BD = 13 cm, AC = 14 cm, dan AE : EC = 5 : 2. jika DE < EB, panjang DE adalah...cm

AE = 5/7 × 14 = 10 cm
EC = 2/7 × 14 = 4 cm
Mis DE = x
Mk EB = 13-x
AE×EC = DE×EB
10×4 = x(13-x)
40 = 13x - x²
x² - 13x + 40 = 0
(x - 8)(x - 5) = 0
x = 8 atau x = 5
Krn DE < EB mk diambil x = 5
Jd DE = 5 cm