Square Measure, used in measuring surfaces, such as cloth, ceilings,
floors, etc.; paving, glazing, and stone-cutting, by the square foot;
roofing, flooring, and slating by the square of 100 feet.
A surface has two dimensions, length and breadth.
A square is a figure that has four equal sides and four right angles.
The unit of measure for surfaces is a square, each of whose sides is a
linear unit. Thus, a square inch is a square, each of whose sides is one
inch long; a square foot is a square, each of whose sides is one foot
long, etc.
The area of a square is the product of two of its sides. Thus, the area
of a surface 3 feet square is 3 × 3 = 9 square feet.
Hence, to find the area of a rectangle:
RULE.--Multiply the length by the breadth expressed in units of the same
denomination.
As the area of a rectangle is found by taking the product of the numbers
representing its length and breadth, it is evident that if the area be
divided by either of those numbers, the quotient will be the other
number. Hence, to find either side of a rectangle when its area and the
other side are given:
RULE.--Divide the area by the given side. The quotient will be the
required side.