Question

Explain how this figure is a trapezium. Which of its two sides are parallel?

Answer 1

If a transversal line is intersecting two given lines such that the sum of the measures of the angles on the same side of transversal is $180\degree$, then the given two lines will be parallel to each other.
Here, $∠ NML + ∠ MLK = 180°$
Hence, $NM||LK$
As quadrilateral $KLMN$ has a pair of parallel lines,
therefore, it is a trapezium.