C2 2016 6 Edexcel

6

(i) cos (θ - π/5) = 1/2
θ - π/5 = π/3 or -π/3 or
θ = 8π/15 or -2π/15

(ii) 4 (1-sin^2x) + 7sinx -2 =0
4sin^2x - 7sinx - 2 = 0
(4sin x +1) (sin x -2) = 0
sin x = -1/4 or sin x = 2 (rejected as it is out of the sine range)
x = 345.5°, 165.5°

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