arc considered optional. They can be o

NOTE To eJCpre'\.S our resuh in Us. g,lllons, W~ so:~ in Ihe Tilbk on lhe insidefronl cowr lh,J( llikr = 10 .lm l "" ~g;'lIon. Htnce, Ihe lah conl"in8( lO'm'XI gallon/ 4 x 1O-' m') "" 2 x 10" g"lIons ofw;Oler.EXAMPLE 1- 7 ESTIMATE Thickness of a page. ESlimJle lhe Ihic~ - .. P RO B l (M SOL v I N Gness of" page of lhis book.APPROACH At firsl you might think Ihal U sp"cial m~asuring d~\'ice. amieromekr (Fig, I-II), is needed 10 m~asur~ th~ thickness of one page sincean ordinary ruler dearly won'l do. But w~ can uS you, and Ihe Olher touches Ihepok SO you eSlimak Ih"l dislance as 2 m (Fig. J -12a). You Ihen pace off Ih~diSlance from Ih~ pole 10 th~ base of Ihe building Wi1h big, I·m-Iong. sleps andyou gN a Inial of 16 sleps or 16m,SOLUTION Now you draw. 10 sc"le. Ihe di;lgr;lm ,hown in Fig. 1-12b usingIhcse me",u r em~nts. You can me