Perhatikan gambar di bawah ini! Tentukan panjang CD! dan panjang EF
CD = x, AD = 8 cm, DE = 6 cm, AB = 18 cm
CA = CD + AD
= x + 8
[tex] \frac{cd}{ca} = \frac{de}{ab} \\ \frac{x}{x + 8} = \frac{6}{18} [/tex]
18x = 6( x + 8 )
18x = 6x + 48
18x - 6x = 48
12x = 48
x = 4 cm
Jadi, panjang CD = x = 4 cm
BC = 5 cm, BE = 7 cm, EA = 3 cm, AD = 9 cm
[tex]ef = \frac{(be \times ad) + (ea \times bc)}{be + ea} \\ = \frac{(7 \times 9) + (3 \times 5)}{7 + 3} \\ = \frac{63 + 15}{10} \\ = \frac{78}{10} [/tex]
EF = 7,8 cm
