Geometry
Angle facts, polygons, circle theorems, similarity and congruence, bearings, proof-by-reasons is the skill being marked.
What this lesson covers
Geometry is a 8-part O Level Mathematics lesson. Each part makes one point and then hands over to the next, so it can be read in a sitting or picked up again at the part you stopped on. It defines the idea in plain words before using it, works through an example step by step, breaks the topic into its parts and compares them, shows where it is used outside the textbook, names the mistakes that cost marks in an exam, ends with a recap of what to remember.
How it begins
A geometry answer of "x = 65°" with no explanation is usually worth one mark out of three. The other two are for the words: "angles in a triangle sum to 180°", "alternate angles are equal", "angle at the centre is twice the angle at the circumference". The examiner is checking that you know why, and the only way to show that is to say so.
The 8 parts
- Geometry is marked on reasons
- Polygons: one formula that does everything
- Circle theorems come from one picture
- Similar and congruent
- Bearings
- Where marks go
- What to remember
- Watch one worked through
Practise Geometry
Everything on QuizByt for O Level Mathematics that goes with this lesson: read it first, then test yourself while it is fresh.
🧠 5 quizzes on Geometry (2 easy, 2 medium, 1 hard)
Work up from easy to hard: the hard quiz asks the O Level exam-style questions on Geometry.
🖨️ Printable worksheet
Geometry on paper for O Level, with room to write the working out. Preview the first page free.
🎮 Games for O Level Mathematics
Number and logic games at the right level for O Level. Passing a quiz on Geometry earns the credits that open them.
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