Given that sin(θ + 45°) + 2 cos(θ + 60°) = 3 cos θ, find the exact value of tan θ in a form involving surds. You need not simplify your answer.
- (i)Given that sin(θ + 45°) + 2 cos(θ + 60°) = 3 cos θ, find the exact value of tan θ in a form involving surds. You need not simplify your answer.[4]
- (ii)Hence solve the equation sin(θ + 45°) + 2 cos(θ + 60°) = 3 cos θ for 0° < θ < 360°.[2]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2019). The mark or mark type is shown in brackets.
- [M1] Use trig formulae and obtain an equation in sin θ and cos θ
- [A1] Obtain a correct equation in any form
- [M1] Substitute exact trig ratios and obtain an expression for tan θ
- [A1] Obtain answer tan θ = (2√2-1) / (1-√6), or equivalent
- [B1] State answer, e.g. θ = 128.4°
- [B1ft] State second answer, e.g. θ = 308.4°
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