By first expressing the equation tan θ tan(θ + 45°) = 2 cot 2θ as a quadratic equation in tan θ, solve the equation for 0° < θ < 90°.
- By first expressing the equation tan θ tan(θ + 45°) = 2 cot 2θ as a quadratic equation in tan θ, solve the equation for 0° < θ < 90°.[6]
Mark scheme
Marking points from the official mark scheme (May/June 2020). The mark or mark type is shown in brackets.
- [M1] Use tan 2A formula to express RHS in terms of tan θ
- [M1] Use tan (A + B) formula to express LHS in terms of tan θ
- [A1] Using tan 45° = 1, obtain a correct horizontal equation in any form
- [A1] Reduce equation to 2 tan² θ + tan θ - 1 = 0
- [M1] Solve a 3-term quadratic and find a value of θ
- [A1] Obtain answer θ = 26.6° and no other
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