Tolong bantu jawab....

Tolong bantu jawab….

1. AD = 8 cm, ED = 6 cm, AB = 18 cm

CD = x = ……?

$frac{cd}{ac} = frac{de}{ab} \ frac{cd}{ad + cd} = frac{de}{ab} \ frac{x}{8 + x} = frac{6}{18} \ 18x = 6(8 + x)$

18x = 48 + 6x

18x – 6x = 48

12x = 48

x = 4 cm

2. AB = 12 cm, AE = 4 cm, DE = 6 cm, CD = 7 cm

EF = ………?

$ef = frac{(de times ab) + (ae times cd)}{de + ea} \ = frac{(6 times 12) + (4 times 7)}{6 + 4} \ = frac{72 + 28}{10} \ = frac{100}{10} \ = 10 : cm$