Answer:
3.46 km is the measure of the base of the triangle.
Explanation:
Base of the prism is an equilateral triangle.
The length of the one of the side or base of the triangle = a
Height of the equilateral triangle,h = 3 km
Area of triangle = A

Height of the triangular prism = h' = 12 km
Area of rectangle =

Area of the triangular prism =


(In triangular prism there are two triangles bases and three rectangles)


a = 3.46 km
3.46 km is the measure of the base of the triangle.