4400 Higher June 2007 Paper 4 Q16
16 A triangle has sides of length 5 cm, 6 cm and 9 cm.
Diagram NOT accurately drawn
Calculate the value of \(x\).
Give your answer correct to 3 significant figures.
(3)
| Scheme | Marks |
|---|---|
| \(9^2 + 5^2 - 2 \times 5 \times 9 \times \cos x = 6^2\) | M1 |
| \(90\cos x = 70\) or \(-90\cos x = -70\) (\(\cos x = \frac{70}{90}\)) | M1 |
| \(x = 38.9\) or better | A1 |
| (3) | |
| (3 marks) |
Notes
M1: or \(\cos x = \dfrac{9^2 + 5^2 - 6^2}{2 \times 5 \times 9}\) M2