A straight line l1 l_1\,l1 passes through the points (1,−5)(1, -5)(1,−5) and (4,7)(4, 7)(4,7). Another straight line l2 l_2\,l2 is perpendicular to l1 l_1\,l1 and passes through the points (k,6)(k, 6)(k,6) and (1,7)(1, 7)(1,7). Determine the value of kkk.
