If the lines $x = ay + b,\, z = cy + d$ and $x = a'z + b',\, y = c'z + d'$ are perpendicular, then (1) $cc' + a + a' = 0$ (2) $aa' + c + c' = 0$ (3) $bb' + cc' + 1 = 0$ (4) $ab' + bc' + 1 = 0$
If the lines $x = ay + b,\, z = cy + d$ and $x = a'z + b',\, y = c'z + d'$ are perpendicular, then\\
(1) $cc' + a + a' = 0$\\
(2) $aa' + c + c' = 0$\\
(3) $bb' + cc' + 1 = 0$\\
(4) $ab' + bc' + 1 = 0$