8.2

cross multiplication property reciprocal property exchange property "add-one" property example two building are being compared one has dimensions of 25 x 12 and 18 x X. find X. X 12cross multiply and divide 18x12=216 / 25=8.6418 = 25 over 18 = 25
 * definion: similar figures - two figures are similar if and only if one is congruent to the image of the oth by a dlation
 * polygon similarity postulate - two polygons are similar if and only if there is a way of setting up a correspondence between their sides and angles such that the following are met.
 * Each pair of corresponding angles is congruent
 * Each pair of corrseponding sides is proportional
 * properties of proportions- let a,b,c and d be any real number
 * if a/b=c/d and b and d /0, then ad = bc
 * if a/b c/d and a,b,c, and d /= 0, then b/a=d/c
 * if a/b c/d and a,b,c, and d /= 0, then a/c = b/d
 * if a/b c/d and b and d /= 0, then a + b / b = c + d / d