Answer:
length of CD = 18 units.
Step-by-step explanation:
In ΔABC and ΔCED,
AB║DE and AD is a transversal line,
m∠ABC = m∠CED [Alternate interior angles]
m∠ACB = m∠DCE [Vertically opposite angles]
ΔABC ~ ΔCED [By AA property of similarity]
Therefore, by the property of similar triangles, corresponding sides will be proportional.
CD = 6
Since, AD = AC + CD
AD = 12 + 6
= 18 units
Therefore, length of CD = 18 units.