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# mind blank...

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### #1will_789

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Posted 23 January 2007 - 11:14 PM

Whats the integral of 2cos2x?

cheers dudes and dudettes

### #2The Wedge Effect

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Posted 23 January 2007 - 11:16 PM

Just use the double angle formulae, and you can integrate more easily from there.

### #3will_789

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Posted 23 January 2007 - 11:24 PM

is it sin2x?

### #4will_789

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Posted 23 January 2007 - 11:28 PM

QUOTE(will_789 @ Jan 23 2007, 11:24 PM)
is it sin2x?

Nope...Jesus...its too late for this maths malarkie. Im off lol

### #5Dave

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Posted 24 January 2007 - 01:39 PM

2cos2x

cos2x = 2cos^2-1

therefore:
2cos2x=4cos^2-2

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### #6dfx

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Posted 24 January 2007 - 02:43 PM

QUOTE(will_789 @ Jan 23 2007, 11:24 PM)
is it sin2x?

Yes.

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Posted 24 January 2007 - 08:52 PM

Using double angle formulae makes this harder really, in fact it's usually the case that double angle formula is used to get away from stuff involving cos^2 x or sin^2 x.

But yeah, I agree with Will and dfx, sin2x is the right answer.
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