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

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seiya_001
2006-01-12 19:24:43

thank you for the information...
god bless..

Ricky
2006-01-12 15:02:58

I have put it on my list to either create or find a website with even the most obscure trig identities.  So far, wikipedia (as always) is the best:

http://en.wikipedia.org/wiki/Trig_identities

seiya_001
2006-01-12 14:19:53

thanks a lot bro
btw, do you have any reference where i can get a sumary of trig identity? thanks again...

Ricky
2006-01-12 13:00:04

That's pi.  Phi is normally the "vertical" (not sure exactly what to call it) angle when you are in spherical coordinates.

To:

First step, as always, is to simplify:

Now it becomes fairly simple, just use the trig identity:

Where a = x and b = nx

Which simplifies to:

seiya_001
2006-01-12 11:39:15

phi as in 180 deg... or is it pi

Ricky
2006-01-12 08:11:24

To:

seiya_001
2006-01-12 02:29:27

can anybody tell me how to change

1     phi
-    ( ∫ A sin x . cos nx dx)
phi    0

into:

A     1     phi
-   .  -   . ∫(sin (1+n)x + sin (1-n)x )dx
phi    2    0

thanks before...