What does “Perpendicular and parallel lines” actually mean in Straight Lines, and why does it matter for JEE?
parallel lines have equal slopes; perpendicular lines have slopes whose product is −1.
In simple words: parallel lines have equal slopes; perpendicular lines have slopes whose product is −1. Getting Perpendicular and parallel lines clear matters because JEE questions on Straight Lines usually test this idea directly, not just a formula you memorised.
Key point
Perpendicular and parallel lines
Common mistake
thinking perpendicular lines have equal slopes.
Memory tip
parallel → equal slopes; perpendicular → m₁·m₂ = −1.
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