Total surface area equals area of 5 rectangular faces + 2 pentagonal faces
Area of 5 rectangular faces
[tex]=5 \times 6 \times 9 km^2[/tex]
[tex]=270 km^2[/tex]
Area of 2 pentagonal faces can be found by drawing 5 isosceles triangles with height as shown in the diagram and multiply the result by 2.
[tex]=5 \times \frac{1}{2} \times 9 \times 6.2 \times 2km^2[/tex]
[tex]=279km^2[/tex]
The toatal surface area is
[tex]=270+279=549 km^2[/tex]
The correct answer is A
