Standard +0.3 This question requires applying the double angle formula cos 2θ = 2cos²θ - 1, then solving a quadratic equation in cos θ, followed by finding angles in the given range. While it involves multiple steps, each step is standard technique from the syllabus with no novel insight required, making it slightly easier than average.
Use correct process to find at least one value of \(\theta\) from equation of form \(k_1\cos^3\theta = k_2\)
M1
Obtain \(42.5\)
A1
Obtain \(317.5\) and no others between \(0\) and \(360\)
A1
## Question 2:
| Answer | Marks | Guidance |
|--------|-------|----------|
| Use $\cos 2\theta = 2\cos^2\theta - 1$ | B1 | |
| Obtain $10\cos^3\theta = 4$ or equivalent | B1 | |
| Use correct process to find at least one value of $\theta$ from equation of form $k_1\cos^3\theta = k_2$ | M1 | |
| Obtain $42.5$ | A1 | |
| Obtain $317.5$ and no others between $0$ and $360$ | A1 | |
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