Edexcel GCSE Higher Maths - Circle Theorems (copy)

Parts of a Circle:

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Circle Theorems:

Alternate Angle Theorem:

The alternate segment theorem is the angle that lies between a tangent and a chord is equal to the angle subtended by the same chord in the alternate segment.

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Angles at the Centre Theorem:

The angle at the centre is twice the angle at the circumference.

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Angles in the Same Segment Theorem:

Angles in the same segment are equal.

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Angles in a Semicircle Theorem:

The angle in a semicircle is 90 degrees.

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Chord of a Circle Theorem:

The perpendicular from the centre of a circle to a chord bisects the chord (splits the chord into two equal parts).

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Tangent of a Circle Theorems:

The angle between a tangent and a radius is 90 degrees. Tangents which meet at the same point are equal in length.

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Cyclic Quadrilateral Theorem:

The opposite angles in a cyclic quadrilateral total 180 degrees.

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