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Help with my trigonometry
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Ladowerf:

--- Quote from: A.R.C. on October 21, 2009, 02:51:03 PM ---Trigga-brother-nometry.

--- End quote ---

Stop being a tribal little friend.

On-topic: Google math help websites.
Otis Da HousKat:

--- Quote from: Ladowerf on October 22, 2009, 10:15:36 AM ---Stop being a tribal little friend.

On-topic: Google math help websites.

--- End quote ---
Stop being homophobic, you working class slob.
mctwist:
They are only true if a=45

Proof (Using degrees):
sin(45) = cos(45)

Test:
a = 45
sin(4*45)-cos(4*45) = 1
sin(2*45)-cos(2*45) = 1
sin(90) = 1
cos(90) = 0
sin(180) = 0
cos(180) = -1
1-0 = 1
0-(-1) = 0+1 = 1

I cannot give you a formula, but this is just an easy way to give a small proof.

You might have had already your test, but it's good to know afterwards too.
Ladowerf:

--- Quote from: Otis Da HousKat on October 22, 2009, 10:16:55 AM ---Stop being homophobic, you working class slob.

--- End quote ---

Oh, I apologize for using the word "friend". I didn't know it was a insult to gay people.
skoposh:

--- Quote from: Maor on October 21, 2009, 01:41:19 PM ---So I have a test tomorrow and I'm stuck at one question.
I need to prove these two equations equal.
sin^4a-cos^4a = sin^2a-cos^2a

Now, I have no idea what I can do from here, or how can I proceed, help please?

--- End quote ---
This is a bit late but:
Google is better help than the Blockland fourms.
http://en.wikipedia.org/wiki/Proofs_of_trigonometric_identities
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