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Paper 3

Circle Theorems

Higher
Practice this
Circle theorem angle diagram

Memorise the main angle theorems.

Key Facts

  • Opposite angles in a cyclic quadrilateral sum to 180°.
  • Centre angle is twice the circumference angle.

Topics Covered

Angle Theorems

What you need to know

  • Angle in a semicircle is 90°.
  • Same segment angles are equal.

Exam Tips

  • Quote the theorem before writing the angle value.

Cyclic Quadrilaterals

What you need to know

  • Opposite angles sum to 180°.
  • Exterior angle equals opposite interior angle.

Exam Tips

  • Mark the arcs and angles clearly.

Key Terms

Cyclic quadrilateral

A quadrilateral whose vertices lie on a circle.

Tangent

A line that touches a circle at one point.

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Common Exam Questions

Angle at centre is 110°. Angle at circumference?

2 markseasyPaper 3

Model Answer

55°

What examiners want to see

  • Centre angle is twice circumference angle.

Angles in the same segment are?

1 markeasyPaper 3

Model Answer

Equal

What examiners want to see

  • State the theorem.

Related Topics

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