9 feet by 9 feet would hold true for its perimeter and area.
Area of rectangle = Length x Breadth = 9x 9= 81sq feet Acc. to me a room has three dimensions length, breadth and height. If you know the area of the woom and length and breadth you can find height.
9 feet by 9 feet=81sq Feet
Sq root of 81 = 9 because 9x9=81Sq root of 121 = 11 because 11x11=1219/11 is the answer.
Your square footage is the length and width or 9x9 or 81sq ft. For cubic you need to include another measurement, that would be the depth. For instance if you want the depth to be 9ft also then your cubic measurement would be 9x9x9 or 729 cu ft.
A yard of Concrete is 3ft x 3ft x 3ft volume. It is usually poured over a 2" gravel sand mix for an additional four inches. So it should cover 36 "/4" = 9 (x 3ft x 3ft), or 81sq ft.The 'square feet' of area that it covers is 324/(depth of the concrete, in inches)