Teach Genie
Teach it back in your own words, spot gaps, and remember it better.
Circle theorem questions are really about spotting structure in a diagram. Look for radii, chords, tangents, and shapes with all vertices on the circle.
The main angle facts come from three clues: equal radii, a tangent touching the circle, and angles standing on the same chord or arc. Start by marking these clues on the diagram before you calculate anything.
Question 1
2 marksB B\,B is a point on the circumference of a circle, centre OOO. AB AB\,AB is a tangent to the circle.
Angle BOA=72∘BOA = 72^\circBOA=72∘
A [ ] is a straight line joining two points on the circumference.
Revision notes for Edexcel GCSE Maths Circle Theorems. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
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Points AAA, BBB and CCC lie on a circle. A tangent touches the circle at CCC. Given that angle ABC=64∘ABC=64^\circABC=64∘ and angle ACB=73∘ACB=73^\circACB=73∘, find the angle between the tangent and chord CBCBCB.
