Paper 2 · Co-ordinate Geometry of the Circle ⏱ Tested in 3 exam questions since 2019 Lesson 6 of 9

The circle 6: Circles with the axes as a tangent

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You’ll learn

  • Use the axis-tangent rules: x-axis tangent ⟹ r = |−f|; y-axis tangent ⟹ r = |−g|
  • Give both solutions when one axis is tangent — one circle on each side
  • Solve chord-on-an-axis problems with Pythagoras: r² = (half-chord)² + (distance)²
  • Parameterise the centre as (k, k) or (k, −k) when both axes are tangents

Most recent exam questions

  • 2024 P2 Q2(c) — deferred
  • 2022 P2 Q3(c)
  • 2019 P2 Q3(b)

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