AREASAll areas are measured in squares.Illustration:Let one side of a square be s.This is a square s or s^{2}.Ifs equals 1 inch then this would be 1 square inch.Ifs equals 1 foot then this would be 1 square foot, etc.Consider the area of the above. The area of A is onesquare s or Sz; of B is s~, etc. The area of the whole isA+ B+ C+ D = s^{2}+ s^{z}+ s^{2 }+ s^{2 }= 4s^{2}. What is the lengthof one side? It is obviously 2s, so in the above the areais 2s x 2s = 4s^{2}.The area of a square is the product of two of its sidesand since both sides are equal, it may be said to be thesquare of its side.NOTE: The area of any plane surface is the measureof the number of squares contained in the object. Theunit of measurement is the square of the unit whichmeasures the sides of the square.AREA OF A RECTANGLEEstablish a side of the small square as s and writethe formula 3s x 4s = Area. But L = 4s and W = 3s, soour formula becomesA=whereA=L=w=L x Warea of a rectanglelength of a rectanglewidth of a rectangleAREA OF A CROSS SECTIONThe cross section of an object is a plane figureestablished by a plane cutting the object at right anglesto its axis. The area of this cross section will be the areaof the plane figure produced by this cut.The area of the cross section is L x W.The most common units are square inches, squarefeet, square yards and in roofing, “squares.”1 square foot= 144 square inches1 square yard= 9 square feet1 square of roofing = 100 square feetAII-16