Answer:
b
Step-by-step explanation:
Given
a cos2x
b
2sinxcosx = sin2x
c
2cos²x - 1 = cos2x
d
1 - 2sin²x = cos2x
b is the expression not equal to the others
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Note
cos2x = cos²x - sin²x = cos²x - (1 - cos²x) = 2cos²x - 1
cos2x = (1 - sin²x) - sin²x = 1 - 2sin²x
