SOLUTION: prove that: 1-2cos (x)= 4(cos(x))^2

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Question 1142795: prove that: 1-2cos (x)= 4(cos(x))^2
Answer by math_helper(2461) About Me  (Show Source):
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prove that: 1-2cos (x)= 4(cos(x))^2
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They are not equal.

To see this, let x=0

LHS: 1-2cos(0) = 1-2 = -1
RHS: 4(cos(0))^2 = 4*1 = 4 (or just observe RHS >= 0)