Area of the trapezium is given by thew formula:-
(Sum of the parallel sides/2)x(distance between them).
Hence, Area=(8+18)/2 x 13= 169 square units.
It can be shown that the diameter of the circle is 13 units.
The two parallel sides of the trapezium are 8 and 18 units respectively.
By constructing triangles on either side of the trapezium, (by dropping perpendiculars from the shorter parallel side to the longer parallel side)and using similarity rules, it can be shown that the middle parallel line, that is, the diameter is wxactly 13 units.
Hence, the area is 169 square units.