Respuesta :

MrGumby
Roughly 80.1 with rounding. 

The height of the figure is 4.9 which you can find with the Pythagorean theorem. Then simply solve by finding each area by itself. 
Area of Trap = height(one base + other base) / 2
height = 10sqrd - 8.7sqrd = sqrt 24.31 = 4.93

Area of trap = 4.93(20.7 + 12)/2 = 80.61