Answer:
132 km^2
Step-by-step explanation:
For this type of question, we’re looking for the surface area (SA) for the shape.
To do this, use the surface area (SA) formula 
SA = 2lh + 2lw + 2hw where l = length w = width & h = height 
But before we go ahead, this formula is only used for triangular shapes. So what we’re going to do is find the surface area and then split it in half.
SA = 2(8)(6) + 2(8)(6) + 2(6)(6) / 2
SA = (2(48) + 2(48) + 2(36)) / 2
SA = (96 + 96 + 72) / 2
SA = 264/2
SA = 132
The surface area is 132 km^2