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MathsMaths165 views·Updated May 26, 2026·4 pages

Mastering Maths: Comprehensive Topic Review

user profile picture
Isha Patel@ishx_0119

Ready to master percentage changes and transformations? These topics might... Show more

1
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Compound Changes

Ever wondered how your savings grow over time or why car values drop each year? Compound changes happen when you apply percentage changes repeatedly - like getting interest on your interest!

The magic formula is: compound value = original × (multiplier)ⁿ. Remember that 25% less means multiply by 0.75, whilst 5% more means multiply by 1.05. The 'n' tells you how many time periods you're dealing with.

Reverse problems work backwards from the final amount. If £3375 becomes your total after 3 years at 50% interest, divide by 1.5³ to find you started with £1000. For unknown time periods, you'll need logarithms - don't panic, your calculator can handle these!

Quick tip: When no original value is given, just pick a round number like £10,000 to make calculations easier.

2
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Simple Interest and Transformations

Simple interest is much easier than compound - you earn the same amount each year using I = p × r × t. If you invest £300 for 2 years at 4% annually, you'll earn £24 total (£12 per year).

Now for something completely different - transformations! These are the four ways to move shapes around: translation (sliding with vectors), reflection (flipping across mirror lines), rotation (spinning around a centre), and enlargement (changing size from a centre point).

Vectors like (3, -4) mean 3 units right and 4 units down. Rotations need three pieces of info: direction clockwise/anticlockwiseclockwise/anticlockwise, angle (usually 90°, 180°, or 270°), and the centre point coordinates.

Watch out: Negative enlargements cause the shape to flip 180° as well as change size!

3
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Tricky Transformations and Invariant Points

Here's where many students get caught out! If two shapes look like one has been rotated but they're different sizes, it's actually an enlargement with a negative scale factor, not a rotation.

The only exception is when the scale factor equals -1 - this has exactly the same effect as a 180° rotation, so either description counts as correct. Your examiner will accept both answers!

Invariant points are spots that don't move during transformations. With translations, points only stay put if the vector is (0,0). For rotations, the centre point stays fixed (unless it's outside the shape). With enlargements, any point that sits exactly on the centre of enlargement won't budge.

Pro tip: Take your time finding all vertices after transformations - rushing leads to shapes drawn in completely wrong orientations!

4
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.

Where can I download the Knowunity app?

You can download the app from Google Play Store and Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

AnnaiOS user

MathsMaths165 views·Updated May 26, 2026·4 pages

Mastering Maths: Comprehensive Topic Review

user profile picture
Isha Patel@ishx_0119

Ready to master percentage changes and transformations? These topics might seem tricky at first, but once you get the hang of the formulas and key principles, you'll be solving problems like a pro.

1
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

Compound Changes

Ever wondered how your savings grow over time or why car values drop each year? Compound changes happen when you apply percentage changes repeatedly - like getting interest on your interest!

The magic formula is: compound value = original × (multiplier)ⁿ. Remember that 25% less means multiply by 0.75, whilst 5% more means multiply by 1.05. The 'n' tells you how many time periods you're dealing with.

Reverse problems work backwards from the final amount. If £3375 becomes your total after 3 years at 50% interest, divide by 1.5³ to find you started with £1000. For unknown time periods, you'll need logarithms - don't panic, your calculator can handle these!

Quick tip: When no original value is given, just pick a round number like £10,000 to make calculations easier.

2
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

Simple Interest and Transformations

Simple interest is much easier than compound - you earn the same amount each year using I = p × r × t. If you invest £300 for 2 years at 4% annually, you'll earn £24 total (£12 per year).

Now for something completely different - transformations! These are the four ways to move shapes around: translation (sliding with vectors), reflection (flipping across mirror lines), rotation (spinning around a centre), and enlargement (changing size from a centre point).

Vectors like (3, -4) mean 3 units right and 4 units down. Rotations need three pieces of info: direction clockwise/anticlockwiseclockwise/anticlockwise, angle (usually 90°, 180°, or 270°), and the centre point coordinates.

Watch out: Negative enlargements cause the shape to flip 180° as well as change size!

3
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

Tricky Transformations and Invariant Points

Here's where many students get caught out! If two shapes look like one has been rotated but they're different sizes, it's actually an enlargement with a negative scale factor, not a rotation.

The only exception is when the scale factor equals -1 - this has exactly the same effect as a 180° rotation, so either description counts as correct. Your examiner will accept both answers!

Invariant points are spots that don't move during transformations. With translations, points only stay put if the vector is (0,0). For rotations, the centre point stays fixed (unless it's outside the shape). With enlargements, any point that sits exactly on the centre of enlargement won't budge.

Pro tip: Take your time finding all vertices after transformations - rushing leads to shapes drawn in completely wrong orientations!

4
of 4
# Year 9-Maths Section 4

Circle Theorems:
*   8 circle theorems in total.

diameter

I

Angle in semicirde:
90°

angle at centre is
twice a

Sign up to see the content. It's free!

  • Access to all documents
  • Improve your grades
  • Join milions of students

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.

Where can I download the Knowunity app?

You can download the app from Google Play Store and Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

Most popular content: Interest

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Most popular content in Maths

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MathsMaths

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Explore essential mathematical concepts including powers, geometry, statistics, and probability. This resource features 65 pages of detailed explanations, diagrams, and examples to enhance your understanding of topics such as right triangles, volume calculations, and data representation. Ideal for students seeking to strengthen their numeracy skills and grasp complex mathematical principles.

1079,7766,318
MathsMaths

GCSE Maths (Higher) // Revision Guide

The only GCSE maths (higher) revision guide you need to get a grade 9! Contains every topic, each with all potential question types and their solutions.

102,33054
M
MathsMaths

Medium Level alerbra

Master challenging maths concepts with this medium level flashcard set designed for grade 7/8 students. Strengthen your problem-solving skills and boost your confidence in maths!

75533
MathsMaths

Comprehensive Maths Concepts

Explore essential mathematical concepts including polynomial theorems, logarithmic properties, trigonometric functions, and integration techniques. This resource covers everything from solving inequalities to understanding exponential functions, providing a solid foundation for A-level mathematics. Ideal for students aiming for top grades.

1221,9901,818
M
MathsMaths

Mastering Maths: Essential Concepts for Grade 10

Boost your math skills with this comprehensive flashcard set covering key concepts for grade 10. Perfect for exam preparation and building a strong foundation in mathematics.

104261
M
MathsMaths

Mastering Medium-Level Maths: Essential Flashcards for Grade 11 Students

Boost your Maths skills with this comprehensive set of flashcards designed specifically for Grade 11 students. Covering medium-level topics, these cards will help you ace your exams and build a solid foundation for advanced Maths.

118823
MathsMaths

Comprehensive Maths Concepts

Explore essential higher mathematics concepts including calculus, trigonometry, polynomials, and vector analysis. This summary covers key topics such as differentiation, integration, quadratic equations, and the properties of circles, providing a solid foundation for exam preparation. Ideal for students seeking a concise yet thorough review of advanced mathematical principles.

S51,93757
P
MathsMaths

Percentage,fractions and decimals

how well do you know percentages,fractions and decimals

72703
M
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maths SOHCAHTOA

Trigonometric ratios SOHCAHTOA for calculating angles and sides in right-angled triangles.

111740

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Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.

12102,3893,038
CriminologyCriminology

Criminology: Crime & Punishment Overview

Comprehensive mindmaps covering key concepts in the Crime and Punishment topic for WJEC Criminology Unit 4. This resource includes detailed insights into the Criminal Justice System, crime prevention strategies, sentencing models, and the roles of various agencies. Ideal for A-Level revision, ensuring you grasp essential theories and legislative processes to excel in your exams.

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Explore in-depth analysis and key quotes for characters in J.B. Priestley's 'An Inspector Calls'. This resource covers Gerald Croft, Inspector Goole, Sheila Birling, Mrs. Birling, Eric Birling, and Eva Smith, focusing on themes of class, gender roles, and social responsibility. Ideal for students aiming for Grade 8 and above.

1025,231901
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Explore key criminology theories and their implications on crime and deviance. This comprehensive summary covers biological, psychological, and sociological perspectives, including labelling theory, right realism, and the impact of social campaigns on policy development. Ideal for A-Level criminology students seeking to understand the complexities of criminal behaviour and the factors influencing crime prevention strategies.

129,746211
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Key Romeo and Juliet themes and analysed quotes

106,619197
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Explore the complex themes of guilt and ambition in Shakespeare's 'Macbeth'. This analysis covers key characters, including Macbeth and Lady Macbeth, their moral dilemmas, and the tragic consequences of their ambition. Ideal for students studying character motivations, thematic elements, and the psychological impact of power. Includes insights on the natural order, manipulation, and the descent into madness.

918,818392

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.6/5App Store
4.7/5Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan SiOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha KlichAndroid user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

AnnaiOS user