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**fusilli_jerry89****Member**- Registered: 2006-06-23
- Posts: 86

√ 2 sin²-cos=0

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**Zhylliolom****Real Member**- Registered: 2005-09-05
- Posts: 412

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**fusilli_jerry89****Member**- Registered: 2006-06-23
- Posts: 86

can you please explain how you got from this to this:

2cos²+cos-2 to cos = -1±√1-(4)(2)(-2)/2(2)

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,659

That would be the Quadratic Equation

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Zhylliolom****Real Member**- Registered: 2005-09-05
- Posts: 412

Yes, it is the quadratic formula. If we let *x* = cos *θ*, then

which may be solved by means of the quadratic formula.

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**fusilli_jerry89****Member**- Registered: 2006-06-23
- Posts: 86

Zhylliolom wrote:

Yes, it is the quadratic formula. If we let

x= cosθ, thenwhich may be solved by means of the quadratic formula.

Oh yeah, how stupid of me

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