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Ordinary Level Mathematics Revision Notes

Topic 2.2: Co-ordinate Geometry

These notes explain Co-ordinate Geometry in simple English so students can understand the topic clearly, not just memorise rules. The Ordinary Level version keeps the focus on the core ideas without unnecessary higher-only pressure.

Curriculum Irish Leaving Certificate
Subject Mathematics
Level Ordinary Level
Premium feature Teacher-style explanations and cleaner study flow
Focus
Understanding before memorising
Interactive
Study tools and guided structure
Question Style
Explained examples and exam practice
Format
Website reading and printable notes

Subtopics Covered

  • The Line
  • The Circle
  • 📝 Exam Style Questions

What Makes This Version Better

  • Cleaner Ordinary Level focus with no unnecessary higher-only material
  • Simple teacher-style explanations before each method
  • Worked examples in clear stages
  • Cleaner page flow for student understanding
  • SEO-friendly website naming and branding
Disclaimer This publication is an independent educational resource developed by ExamsLogic and compiled by experienced educators. It is based on publicly available official curricula, including Cambridge, Pearson Edexcel, IB, and the Irish Leaving Certificate. This product is not endorsed by, affiliated with, or sponsored by any examination board or governing authority. All registered trademarks remain the property of their respective owners.
Start Reading Open Study Tools

Learning Objectives

What You Should Be Able To Do

    Interactive Study Tools

    These tools are here to help students slow down and think about the method before rushing to an answer.

    Tool 1

    Study Planner

    Use this to break a topic into small study sessions.

    Plan: A clear breakdown will appear here.
    Tool 2

    Method Reminder

    This quick guide reminds students what to do when they feel stuck.

    • Read the story: what is the question really asking?
    • Choose the method: identify the correct idea before calculating.
    • Show the reason: do not skip the logic.
    • Check the answer: make sure it fits the situation.

    1. The Line

    Simple explanation: This section explains the geometry ideas slowly and clearly so students can understand both the picture and the reason.

    Understanding equations of lines and the relationship between points.

    Slope (m) = (y2 - y1) / (x2 - x1)
    Equation of line: y - y1 = m(x - x1)
    Examiner Tip
    💡 Examiner Tip: Parallel lines have the same slope ($m1 = m2$). Perpendicular lines have slopes that multiply to -1 ($m1 imes m2 = -1$). This is a vital shortcut!

    2. The Circle

    Simple explanation: This section explains the geometry ideas slowly and clearly so students can understand both the picture and the reason.

    A circle with center (h, k) and radius r.

    (x - h)² + (y - k)² = r²
    Common Mistake
    ❌ Common Mistake: Forgetting to square the radius when writing the circle equation. If the radius is 3, the end of the equation must be 9 ($3^2$), not 3!
    Exam Trap
    ⚠️ Exam Trap: A line is tangent to a circle if the perpendicular distance from the center of the circle to the line equals the radius. Use the "perpendicular distance from a point to a line" formula!

    📝 Exam Style Questions

    Simple explanation: This section explains the geometry ideas slowly and clearly so students can understand both the picture and the reason.

    Easy Q1: Find the slope of the line passing through (2, 3) and (5, 9).

    Medium Q2: Find the equation of the circle with center (0, 0) and radius 5.

    A1: Slope = (9 - 3) / (5 - 2) = 6 / 3 = 2.

    A2: x² + y² = 25.