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Q3 — Circle theorem proof (4 marks)

GCSE · Mathematics · CCEA · GGeometry and measures

Question

Question. Points A, B, C, D lie on a circle, centre O. AC is a diameter. Angle BAC = 28° and angle DCA = 35°. Calculate angle BDC, giving a reason for each step.

Mark scheme.

  • B1: angle ABC = 90° (angle in a semicircle).
  • M1: angle BCA = 180 − 90 − 28 = 62° (angle sum of triangle).
  • M1: angle BDC = angle BAC = 28° (angles in the same segment, both subtended by arc BC) — accept any equivalent valid route giving 28°.
  • A1: 28°, with all reasons stated. (4)

4 marks · take your time before peeking.

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Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.