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Circle TheoremsCambridge IGCSE Maths: Subtopic test

10 questions, 26 marks

Cambridge IGCSE Maths

Circle Theorems

Total 26 marks

Name

Class

Date

  1. 1
    A circle with centre O has points A, B and C on its circumference, where AC is a diameter. A tangent line touches the circle at point D.
    (a)
    Points A, B and C lie on a circle with centre O, where AC is a diameter. If angle ABC is the angle subtended at B by the diameter AC, what is the size of angle ABC?
    [1 mark]
    • A90°90°
    • B180°180°
    • C45°45°
    • DCannot be determined
    (b)
    A tangent to the circle touches at point D, and OD is a radius drawn to that point. What is the size of the angle between the tangent and OD?
    [1 mark]
    • A180°180°
    • B45°45°
    • C0°0°
    • D90°90°
    (c)
    Given angle BAC = 35°35° in triangle ABC (where AC is a diameter), find angle BCA.
    [1 mark]
    • A35°35°
    • B55°55°
    • C90°90°
    • D145°145°

    Total for question 1: 3 marks

  2. 2
    Points P, Q, R and S lie on a circle with centre O. The angle at the centre, angle POR, is 128°128°, and PQRS forms a cyclic quadrilateral.
    (a)
    Points P, Q and R lie on a circle with centre O. The angle at the centre, angle POR, is 128°128°. Find angle PQR, the angle at the circumference subtended by the same arc PR, giving a geometric reason.
    [2 marks]
    (b)
    PQRS is a cyclic quadrilateral. Given that angle PQR = 64°64° (from part (a)), find angle PSR, giving a geometric reason.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A circle with centre O contains two chords, EF and GH, and a tangent from an external point J touching the circle at two points.
    (a)
    Two chords, EF and GH, of a circle with centre O, are both known to be equidistant from O. Given EF = 6 cm, find the length of GH, giving a geometric reason.
    [3 marks]
    (b)
    From an external point J, two tangents are drawn to the circle, touching at points K and L. Given JK = 9 cm, find JL, and state the two geometric facts used to justify your answer.
    [3 marks]

    Total for question 3: 6 marks

  4. 4
    A circle has a tangent touching at point T, with chord TW drawn from T, and point V on the circle in the alternate segment. A further point U also lies on the circle, forming cyclic quadrilateral TWVU.
    (a)
    A tangent touches a circle at point T. A chord TW is drawn from T, and angle between the tangent and chord TW is 58°58°. A point V lies on the circle in the alternate segment. Using the alternate segment theorem, find angle TVW, giving a full geometric reason.
    [4 marks]
    (b)
    TWVU is a cyclic quadrilateral inscribed in the same circle, with vertices in the order T, W, V, U. Angle TVW =58°= 58° (from part (a)) and angle WTU =95°= 95°. Find angle WVU, and hence find angle TVU, showing all reasoning.
    [4 marks]
    (c)
    Explain, using circle theorem vocabulary, why angle TVW (found in part (a)) and the angle at the centre subtended by the same arc TW would be related by a factor of two, and calculate that centre angle.
    [5 marks]

    Total for question 4: 13 marks

End of questions