IGCSE Maths / Circle theorems

Intersecting chords inside a circle revision notes

Edexcel International GCSE Maths (4MA1), chapter 17: Circle theorems, specification point 4.6a. Part of the full course.

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When two chords cross inside a circle, the products of the two pieces of each chord are equal. This lets you find a missing length or form and solve a quadratic equation.

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
• Reasoning chains with circle theorems
• Multi-step circle theorem problems
• Intersecting chords from a point outside the circle