A rectangular space with a length of 45 feet and a width of 10 feet measures 450 square feet. The square footage of a rectangular area is the product of the length and width of the area.
If the length of the room were increased, the width of the room would need to shrink in order to have the room remain 450 square feet. A rectangular space with a length of just 25 feet needs to be 18 feet wide to occupy 450 square feet. A 450-square-foot space does not need to be rectangular, but different geometric formulas are needed to calculate the square footage of circular, trapezoidal and triangular spaces.