20 10 Hengyang senior high school entrance examination mathematics 12 questions
Let A(a, 0), then the abscissa of C(a, k/a) and d is a/2, and the ordinate of d is 2k/a (obtained by substituting x=a/2 into y=k/x). Since d is the midpoint, the ratio of B(a, 4k/a), △OAC and △OAB area.