4400 Higher November 2008 Paper 3 Q16
16

Diagram NOT accurately drawn
\(A\), \(B\), \(C\) and \(D\) are points on a circle.
\(PA\) is the tangent to the circle at \(A\).
Angle \(PAD = 54^\circ\), angle \(ACB = 36^\circ\) and angle \(ADC = 78^\circ\).
(a)
(i) Find the size of angle \(ACD\).
(ii) Give a reason for your answer.
(2)(b) Explain why \(BD\) is a diameter of the circle. (2)
(c)
(i) Work out the size of angle \(ABC\).
(ii) Give a reason for your answer.
(2)| Scheme | Marks |
|---|---|
| (i) Answer: 54 | B1 |
| (ii) Answer: angle between chord & tangent = angle in alternate segment | B1 |
| (2) |
Notes
B1: Accept ‘alternate segment’
| Scheme | Marks |
|---|---|
| angle \(BCD = 90^\circ\) | B1 |
| angle in a semicircle is a right angle | B1 |
| (2) |
Notes
B1: Accept if ‘semicircle’ seen
| Scheme | Marks |
|---|---|
| (i) Answer: 102 | B1 |
| (ii) Answer: opposite angles of a cyclic quadrilateral are supplementary | B1 |
| (2) | |
| (6 marks) |
Notes
B1: Accept if ‘opposite’ and ‘cyclic’ seen
(‘Alternate segment’ is an alternative)