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# Proof - Golden Ratio. watch

1. Prove that the golden ratio...

½(1+√5) = 2sin18 + 1

Help Appreciated.
2. We have cos(36) = sin(54) (*)
And cos36 = 1 - 2sin218
and sin54 = 3sin18 - 4sin318
The plug your number for sin18 = 1/2(√5 -1) from your equation (*)
It's just neccesary condition for it as you need to show (*) has no other roots

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Updated: November 11, 2005
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