Дано: а||Ь, АВ ∈ a, CD ∈ b AD BC = E.

Given: a || b, AB ∈ a, CD ∈ b, AD BC = E.

Using the given information, we can deduce the following:

1. Since a || b, we know that the lines a and b are parallel.

2. AB and CD are line segments lying on the parallel lines a and b, respectively.

3. AD and BC are also line segments lying on the parallel lines a and b, respectively.

4. The equality AD BC = E suggests that the ratio of the lengths of the line segments AD and BC is equal to a constant E.

In summary, we have two parallel lines a and b and line segments AB, CD, AD, and BC lying on these lines. The given equality implies that the ratio of the lengths of AD and BC is constant and equal to E.