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Rosie's Papers Set A Paper 1 · Q6

Paper 1TrigonometrySequences & series

Find the simplified value given by the below sum, where xx is in degrees.

∑x=190cos⁡4x.\sum_{x=1}^{90}\cos4x.
A−1-1
B4545
C12\frac12
D11
E00
F−12-\frac12

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