IGCSE Maths / Circle theorems

Reasoning chains with circle theorems revision notes

Edexcel International GCSE Maths (4MA1), chapter 17: Circle theorems, specification point 4.7a. Part of the full course.

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Circle-theorem questions often need a chain of angle calculations, with a reason for each step. Read the diagram first, then use the full standard statement for each reason.

More lessons in Circle theorems

• Parts of a circle and cyclic quadrilaterals
• Tangent and radius, and two tangents from a point
• The angle at the centre is twice the angle at the circumference
• The angle in a semicircle
• Angles in the same segment
• Opposite angles of a cyclic quadrilateral
• The alternate segment theorem
• Using the alternate segment theorem in a reasoning chain
• Multi-step circle theorem problems
• Intersecting chords inside a circle
• Intersecting chords from a point outside the circle