help needed

You cannot find the surface are because it is not 3 dimensional but maybe I could find the area.

I think I need more info ... like maybe that it is a trapezium for example ???

I/m assuming that we have a trapezoid

The height  = sqrt (9^2 - 7^2 )  =  sqrt ( 32)  =  4sqrt (2)

So....the surface area is

height * (  sum of the bases)   / 2  =  

4 sqrt (2) * ( 5 + 7)  / 2  =

4 sqrt (2)  *  12/2  =

4 sqrt (2)  * 6  =

24 sqrt (2)  dm^2     = about  33.94 dm^2