Grade 9 Optional Math, Explained
CDC’s Optional Mathematics for Grade 9, lesson by lesson: relations and functions, trigonometry, coordinate geometry, transformations, vectors, statistics and limits, every method worked step by step, a graph for every question, every exercise answered.
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- Unit 1 Algebra How can a pot of boiling water tell you how high up a mountain you are? The answer is a rule that can be read backwards. Algebra
- Unit 2 Trigonometry A map gives Bhaktapur’s place as an angle. How do you turn it into kilometers, and what could the sine of 870° possibly mean? Trigonometry
- Unit 3 Geometry Where on a highway is the spot as far from one village as the other? Rules become equations, and a flip, a turn or a zoom a rule too. Geometry
- Unit 4 Vector Walk 3 km east, then 4 km north: how far are you from where you began, and which way? Some quantities need a direction as well as a size. Vectors
- Unit 5 Statistics Lalitpur’s air was six times dustier in April than in July. How do you measure how far a set of numbers swings around its middle? Statistics
- Unit 6 Limit Add ½ + ¼ + ⅛ + … for ever: does the sum keep growing, or settle on a number? What a value gets ever closer to without reaching it. Limits and continuity
Practice
- Exam practiceevery question in the book
- Unit quizpractise the units you choose, at your level
- Grade 9 final exam model papersfull practice papers made to the official grid
How to use this book
Each unit covers its part of the curriculum in the order of CDC’s textbook, whose page numbers are under each unit’s title; whichever book your school uses, you can read it alongside. Inside you’ll find:
- Worked examples: try them first; the answer stays hidden until you open it.
- Try it questions and each unit’s questions at the end, with hints and answers to open when you’re ready.
- Diagrams to play with: drag, slide and change things to see what happens.
- Did you know? boxes with the stories and surprises behind the maths.
A companion to your textbook by Science Playground, not published by or connected with CDC, and not a replacement for the textbook: study from the book your school uses, and where the two differ, follow your teacher. Every fact here has been checked against the textbook and other reliable sources, but these pages have not yet been reviewed by subject experts. If you find a mistake, please tell us.