Circle theorems and angle chains
3 exam-style questions. Answers and the mark for each step are on the last page.
- Question 1
(a) ABCD is a cyclic quadrilateral, with its vertices in that order around the circle. Angle BAD is (3x + 14) and angle BCD is (5x + 6) Work out angle BAD.
- Question 2
(a) A, B, C and D lie in that order on a circle. AB = AD. Angle ABD is (3x 4) and angle BCD is (4x + 18) Work out angle BAD. You must show your working.
- Question 3
A, B, C and D are consecutive vertices of a cyclic quadrilateral. Angle BCD is . AB = AD.
(a) Find angle BAD.
(b) Find angle ABD.
Answers and marks
Question 1
(a) °
- P1 Establishing or an equivalent valid method.
- P1 Establishing or an equivalent valid method.
- A1 Correct answer: °
Question 2
(a) °
- P1 Establishing or an equivalent valid method.
- P1 Establishing or an equivalent valid method.
- A1 Correct answer: °
Question 3
(a) °
- M1 Opposite angles in a cyclic quadrilateral sum to 180 degrees.
- A1 Correct answer: °
(b) °
- M1 AB=AD makes triangle ABD isosceles.
- A1 Correct answer: °