#trig identities

13 messages · Page 1 of 1 (latest)

crystal sapphire
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Can someone help

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lone robin
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do something like this: replace 2x with A, use trig identities to get a hidden quadratic, solve for A

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ezpz 😎

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$2\cos^2a - \cos{a} - 1 = \sin^2a$

terse ospreyBOT
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i love skips!!!! :3

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lone robin
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you get this beautiful equation

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and then you can use good old $\sin^2a + \cos^2a = 1$

terse ospreyBOT
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i love skips!!!! :3

434405709321338895.png
lone robin
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rearrange to get a quadratic in terms of cos(a), solve for cos(a), find 2x

crystal sapphire
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I’ve ended up with cosa=2

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But u don’t think that’s right

lone robin
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,w 2(cos(2x))^2 - cos(2x) - 1 = sin(2x)^2

terse ospreyBOT