can anyone help me in this

Question

Quadrilateral ABCD is a parallelogram. What is BC?

BC = 

Answer 1

The key here is to use what we know about triangles and parallel lines. First, note that ∠BQA is congruent to ∠QBC since BQ is a transversal of parallel lines BC and AD. This means that ∇ABQ is isosceles, so AQ must also be 18 in length. Similarly, ∠CQD is also congruent to ∠BCQ for the similar reasons. Also note that CD is also length 18 because ABCD is a parallelogram. Hence, QD is also length 18, which makes AD have length 36. BC is congruent to AD, so BC must also be 36.

Answer 2

BC = AD

if AQ = QD = AB = 18, then BC =2(18)= 36

visually AQ appears to = AB, and Q appears to divide AD in half.