Question

MATHEMATICS G
If 2cosx + 2cos3x = cosy and 2sinx + 2sin3x = siny then cos 2x =
(A)
-7
8
(B)
1
8
(C) 1
8
(D) 7
8
А
B
с
Mark For Review & Next
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Answer 1

Answer:

cos y=cos 2x

Step-by-step explanation:

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