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Brainlag Learn / GCSE Maths

Circles and circle theorems

The parts of a circle, the circle theorems and how to give them as reasons, tangents, chains of reasoning, and the equation of a circle centred at the origin with its tangents.

Lessons

  1. Parts of a circleRadius, diameter, chord, tangent, arc, sector and segment, and why two radii always make an isosceles triangle. 15 min, free
  2. The circle theoremsThe angle facts for points on a circle, and the exact reason to write next to each one. 25 min, with the Circle theorems simulation, free, Higher tier
  3. TangentsThe right angle between a tangent and a radius, two equal tangents from a point, and the alternate segment theorem. 25 min, with the Circle theorems simulation, Plus, Higher tier
  4. Chains of reasoningQuestions that need two or three facts in a row, with algebra, and a short proof. 25 min, Plus, Higher tier
  5. The equation of a circlex² + y² = r² for a circle centred at the origin, points on it, and the tangent at a point. 25 min, with the Graphing Calculator, Plus, Higher tier

Practise and test

AQA, Pearson Edexcel and OCR are registered trade marks of their owners. Brainlag Learn is independent: it is not affiliated with or endorsed by any exam board, and every question on it is original.