(i) Through (5, 6) and (2, 3); through (9, −2) and (6, −5)
Let m1 be the slope of the line joining (5, 6) and (2, 3) and m2 be the slope of the line joining (9, −2) and (6, −5).
Therefore, the given lines are parallel.
(ii) Through (9, 5) and (−1, 1); through (3, −5) and (8, −3)
Let m1 be the slope of the line joining (9, 5) and (−1, 1) and m2 be the slope of the line joining (3, −5) and (8, −3).
Therefore, the given lines are parallel.
(iii) Through (6, 3) and (1, 1); through (−2, 5) and (2, −5).
Let m1 be the slope of the line joining (6, 3) and (1, 1) and m2 be the slope of the line joining (−2, 5) and (2, −5).
Therefore, the given lines are perpendicular.
(iv) Through (3, 15) and (16, 6); through (−5, 3) and (8, 2).
Let m1 be the slope of the line joining (3, 15) and (16, 6) and m2 be the slope of the line joining (−5, 3) and (8, 2).
Therefore, the given lines are neither parallel nor perpendicular.