Paper 2 · Co-ordinate Geometry of the Line ⏱ Tested in 5 exam questions since 2017 Lesson 6 of 9

The line 6: Angle between two lines

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You’ll learn

  • Find the angle between two lines with tan θ = ±(m₁ − m₂)/(1 + m₁m₂)
  • Read slopes from y = mx + c form — rearrange general-form lines first
  • Find the acute angle, then take 180° − θ for the obtuse angle
  • Keep both ± cases to find the two slopes that make a given angle with a line

Most recent exam questions

  • 2025 P2 Q1(a)(ii) — deferred
  • 2025 P2 Q1(b)
  • 2022 P2 Q2(c)
  • 2020 P2 Q1(b)
  • 2017 P2 Q4(b)

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