The area of a rectangle is calculated as the product of base width and height. In the given case, these values are 6 km and 11 km; or 11 km and 6 km. In either case, the area of rectangle will be 11 km x 6 km = 66 square km. There is no minimum or maximum area, both are the same; 66 square km.
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If the rectangle measures 6 km by 11 km, the area has to be 66 square km. From the formula "area of a rectangle = base of a rectangle * height of a rectangle", we would multiply the 6 and 11 to get 66. It wouldn't make a difference which one is which since we would still get 66. 66 square km would be the minimum and maximum areas of the rectangle; it would be the only area for the rectangle.