Question 98831


       find the value of Y so that the line through (-2,-1) and (10,y) is perpendicular to the line through (6,-2) and (5,7)

     When two lines are perpendicular the product of their slopes =-1

            slope of line through (-2,-1) and (10,y) = y-(-1)/10-(-2)
                                                   m = y+1/10+2
                                                     = (y+1)/12

           slope of line through (6,-2)  and (5,7) = (7-(-2))/5-6

                                                 M = 7+2/-1
                                                   = -9

                                     m.M = -1
                                    (y+1).(-9)/12 = -1
                                          (y+1) = -1.12/-9
                                           y+1 = 4/3
                                             y = 4/3-1
                                               = 4-3/3 = 1/3

                    value of y = 1/3