June 2022 Paper 1 Q18
18 In triangle \(RST \qquad RS : ST = 1 : 4\)
Not drawn accurately
Work out the exact value of \(\sin\theta\). [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(\sin 135^\circ = \dfrac{\sqrt{2}}{2}\) or \(\dfrac{1}{\sqrt{2}}\) | B1 | oe could be embedded in the calculation |
| \(\dfrac{\sin\theta}{x} = \dfrac{\sin 135}{4x}\) | M1 | oe \(x\) may be a different letter (would need to be the same letter for both sides) or numerical values using multiples of 1 and 4 used |
| (\(\sin\theta =\)) \(\dfrac{\sqrt{2}}{8}\) | A1 | oe eg \(\dfrac{1}{4\sqrt{2}}\) |
Additional guidance
| Penalise incorrect further working Condone \(\theta = \sin^{-1}\dfrac{\sqrt{2}}{8}\) seen in answer as long as \(\sin\theta = \dfrac{\sqrt{2}}{8}\) seen in working |