Foundation November 2019 Paper 3 Q31
31 Use trigonometry to work out the value of \(x\). [2 marks]
Not drawn accurately
| Answer | Mark | Comments |
|---|---|---|
| Alternative method 1 | ||
| \(\cos 39 = \dfrac{x}{20}\) or \(20 \times \cos 39\) | M1 | oe eg \(\sin (90 - 39) = \dfrac{x}{20}\) or \(\sin 51 = \dfrac{x}{20}\) or \(20 \times \sin 51\) |
| 15.5(4…) | A1 | allow 16 with M1 seen |
| Alternative method 2 | ||
| \(20^2 - (20 \times \sin 39)^2\) | M1 | oe eg \(20^2 - (20 \times \cos 51)^2\) |
| 15.5(4…) | A1 | allow 16 with M1 seen |
Additional guidance
| \(\cos = \dfrac{x}{20}\) unless recovered | M0 |
| \(20 \times 0.78\) | M1 |
| \(20 \times 0.78\) with an answer of 16 | M1A1 |
| \(20 \times 0.78\) with an answer of 15.6 | M1A0 |
| \(20 \times 0.77\) | M1 |
| \(20 \times 0.77\) with an answer of 16 | M1A1 |
| \(20 \times 0.77\) with an answer of 15.4 | M1A0 |
| cos (39 \(\times\) 20 unless recovered | M0 |
| Answer from scale drawing with no trigonometry | M0A0 |