4MA0 Foundation January 2018 Paper 2R Q17
17 Here is a right-angled triangle.
Diagram NOT accurately drawn
Calculate the length of \(BC\).
Give your answer correct to 3 significant figures.
(3)
| Scheme | Marks |
|---|---|
Eg \(\sin 20 = \dfrac{BC}{8.4}\) or \(\dfrac{BC}{\sin 20} = \dfrac{8.4}{\sin 90}\) or \(\dfrac{\sin 20}{BC} = \dfrac{\sin 90}{8.4}\) | M1 |
| \(8.4\sin 20\) or \(\dfrac{8.4}{\sin 90} \times \sin 20\) or \(8.4\cos 70\) | M1 |
| 2.87 | A1 |
| (3) |
Notes
M1: Or for \(AC\) or angle \(B\) evaluated correctly AND then used in a correct method to find \(BC\)
Eg \(BC^2 + (7.89(34...))^2 = 8.4^2\) or
Eg \(\tan 20 = \dfrac{BC}{7.89(34...)}\)
M1: For a complete method
A1: Accept 2.87(296...) rounded or truncated to at least 3 SF