Theory:

A trapezium is a quadrilateral whose two opposite sides are parallel, but the other two are not parallel.

$$AD$$ and $$BC$$ are two parallel edges are termed as bases.
$$AB$$ and $$CD$$ are two non parallel edges are termed as lateral sides.
In trapezium, whose lateral sides ($$AB$$) $$=$$ ($$CD$$) are equal, then the trapezium is known as isosceles trapezium.

Properties:
• The bases of the trapezium are parallel to each other ($$AD || BC$$).

• The sum of its angles is $$360°$$.

• The diagonals of a regular(all sides and angles are equal) trapezium bisect each other. In regular trapezium ($$AB = BC = CD = DA$$) and ($$∠A = ∠B = ∠C = ∠D$$).