Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1 2006-06-24 10:12:47

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

√ 2 sin²-cos=0

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## #2 2006-06-24 13:35:08

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

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## #3 2006-06-24 14:05:11

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

### Re: Trigonometry

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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## #4 2006-06-24 14:29:35

MathsIsFun
Registered: 2005-01-21
Posts: 7,660

### Re: Trigonometry

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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## #5 2006-06-24 15:19:31

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

### Re: Trigonometry

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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## #6 2006-06-26 12:35:26

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

### Re: Trigonometry

Zhylliolom wrote:

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

which may be solved by means of the quadratic formula.

Oh yeah, how stupid of me

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