Trapezoid area with sides 2,4,9,8 equal to 21.93
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
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 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
2
·
√c2 - ()2
(b-a)2+c2-d2
2·(b-a)
=
2+4
2
·
√92 - ()2
(4-2)2+92-82
2·(4-2)
=
6
2
·
√92 - ()2
22+92-82
2·2
=
6
2
·
√81 - ()2
4+81-64
4
= 3
·
√81 - ()2
21
4
= 3
·
√81 - 5.252
= 3
·
√81 - 27.5625
= 3
·
√53.4375
= 3
·
7.31
=
21.93
Answer: trapezoid area with sides 2,4,9,8 equal to 21.93