SOLUTION: Prove that: cos(72°) = (1/2)sqrt(4sin²(63°) -1)

SOLUTION: Prove that: cos(72°) = (1/2)sqrt(4sin²(63°) -1)

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Question 1191001: Prove that: cos(72°) = (1/2)sqrt(4sin²(63°) -1)
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
They're not equal.
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