Final answer:
To find the length of AB, set up a proportion using the corresponding sides of the similar trapeziums. AB = (12 * 18)/5 = 43.2 cm.
Step-by-step explanation:
To find the length of AB, we can set up a proportion using the corresponding sides of the similar trapeziums.
Since ABCD and AEFG are similar, we have:
AB/EF = BC/EG
AB/12 = 18/5
Cross multiplying, we get AB = (12 * 18)/5 = 43.2 cm
Therefore, the length of AB is 43.2 cm.