Trapezoid area with bases 81,121 and height 40 equal to 4040
A trapezoid is a quadrilateral whose two sides are parallel (bases) and the other two are not parallel (sides).
Trapezoid area formula 
where a and b are bases, h is height
where m is the middle line, h is the height
where d1,d2 are diagonals, α° is the angle between them
where a and b are the bases, c and d are the sides
where r is the radius of the inscribed circle, α° is the angle between the base and the sideSolution:
S =
(a+b)·h
2
=
(81+121)·40
2
=
202·40
2
=
8080
2
=
4040
Answer: the area of a trapezoid with bases 81,121 and height 40 equal to 4040