Square meter, square kilometer, square millimeter, etc.
A circle with a radius of 6 units has an area of 113.1 square units.
area is labelled in square units because, area is a two dimensional quality (LW) and a square is the simplest two dimensional shape to express area in.
You cannot express an area in units of length.
36 square units. You can't express a perimeter in square units; a perimeter is a length expressed in ordinary units. If the perimeter of this square is 24 units then the answer above is correct.
Area is not expressed in feet. You can express area in square units, such as square kilometers, square meters, square miles, or square feet.
Metres to measure the dimensions and then express it in terms of square metres.
Because an area is in a two dimensional plane. Thus you express it in "squares" not straight lines of space taken up.
metre
VA
units with perimeter square units with area
It is not clear what you mean with "units of power".
A rectangular area 9 units by 7 units has an area of 63 square units.