Putting x = 0 in 3x + 4y = 12 3 × 0 + 4y = 12 ⇒ y =
12
4
= 3 ∴ Point of intersection on y – axis = (0, 3) Again, putting y = 0 in 3x + 4y = 12 3x + 4 × 0 = 12 Þ 3x = 12 Þ x = 4 ∴ Point of intersection on x – axis = (4,0) ∴ OA = 4 and OB = 3 ∴ AB = √OA2+OB2 = √43+32 = √16+9 = √25 = 5 units