Kerala SCERT · Mathematics Part 1 · Standard IX · Chapter 5

Irrational Numbers അഭിന്നകഗുണനം

Multiplying and dividing numbers like √2 and √3, writing them in simplest form, and using them to find the areas of triangles – all the way to Heron's famous formula. An interactive, animated self-study guide: the basics from earlier classes, every idea of the chapter with real-life examples, animated solutions to every textbook question, a revision sheet, and a model test with a fully solved paper.

How to use this guide

🎬 Watch the animations

Every idea has a step-by-step animation. Press Next ▶ to move one step at a time, or ▶▶ Auto play to watch it like a video. You can go back any time.

🖐️ Play with the numbers

Sliders change side lengths, decimal places and scale. Watching the numbers and pictures change together is the fastest way to feel why a rule is true.

✍️ Try before you see

Questions come with a Show answer button. Always attempt the question in your notebook first, then check. The quizzes give instant feedback.

📖 Textbook links

Purple മലയാളം words are the exact terms used in your textbook, so you can match every page here with the book (pages 83–98).

Learning path

Follow the pages in order. If you remember square roots and Pythagoras well, you may skim pages 1–4, but do try their quizzes.

Part A · Build the foundation (nothing assumed)
Part B · The chapter, idea by idea
Part C · Use it, revise it, test yourself

The chapter in one picture

🐚 The square-root spiral: √2, √3, √4, … are real lengths

Start with a right triangle with legs 1 and 1: the hypotenuse is √2. Add a new leg of length 1 at right angles to that hypotenuse and you get √3, then √4 = 2, √5, … Every one of these is an exact length you can draw, even though most of them can never be written as a fraction. This chapter teaches you to multiply and divide such numbers and to use them for areas.

Quick glossary (Malayalam ↔ English)

Textbook termEnglishMeaning
അഭിന്നകസംഖ്യIrrational numberA number that cannot be written as a fraction p/q, e.g. √2, √3, π
ഭിന്നസംഖ്യFraction / rational numberCan be written as p/q: ½, 0.75, 3
വർഗമൂലംSquare root√x is the positive number whose square is x
വർഗംSquare (of a number)x² = x × x
ഗുണനം / ഹരണംMultiplication / division√x × √y = √(xy); √x ÷ √y = √(x/y)
ദശാംശംDecimal1.414… is the decimal form of √2
പരപ്പളവ് / ചുറ്റളവ്Area / perimeterSpace inside / length around
സമഭുജത്രികോണംEquilateral triangleAll three sides equal; height = (√3/2) × side
സമപാർശ്വത്രികോണംIsosceles triangleTwo sides equal
ലംബകംTrapeziumQuadrilateral with one pair of parallel sides
സമഷഡ്ഭുജംRegular hexagonSix equal sides = six equilateral triangles
ഹെറോൺ സൂത്രവാക്യംHeron's formulaArea = √(s(s−a)(s−b)(s−c)), s = half the perimeter

Made for self-learning. Works offline – every page is a single file. Study material prepared by Claude for Madhu's family study folder, October 2026.