Question 55 of 104 in Unit 6

Shape and Space 6

1 mark · Easy

In a circle, points A, B, C, D lie on the circumference. Angle ABC = 80°. Find angle CDA. Give a reason for your answer.

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100° (±0)

Must show: Reason: Opposite angles of a cyclic quadrilateral sum to 180°

Common mistakes: Subtracting from 360°

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Marking points

B1 · 1 mark · Correct answer with correct supporting reason.

Worked solution

Opposite angles in a cyclic quadrilateral add to 180°:

Reason: Opposite angles of a cyclic quadrilateral sum to 180°.

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