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Official 2020 Paper 1 · Q18

Paper 1TrigonometryAlgebra

Find the number of solutions and the sum of the solutions of the equation

1−2cos⁡2x=∣cos⁡x∣1-2\cos^2 x=|\cos x|

where 0≤x≤180∘0\leq x\leq180^\circ.

ANumber of solutions =2=2 Sum of solutions =180∘=180^\circ
BNumber of solutions =2=2 Sum of solutions =240∘=240^\circ
CNumber of solutions =3=3 Sum of solutions =180∘=180^\circ
DNumber of solutions =3=3 Sum of solutions =360∘=360^\circ
ENumber of solutions =4=4 Sum of solutions =240∘=240^\circ
FNumber of solutions =4=4 Sum of solutions =360∘=360^\circ

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