Hi,
Are the general solutions for cos(x) = cos(a), x = 2*pi*k +/- a (where k is an integer)? If so, I was trying to find the general solution to cosx = 0, I thought it would be 2*pi*k +/- pi/2, however there solution was pi/2 + k*pi. How did they get there solution?
Thanks
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Last edited by kawaiipotato; 21 Oct 2017 at 10:23 AM.
Sxc avatar made by a sxc person: carrotontheground http://community.boredofstudies.org/...otontheground/
Oh, ok. Yeah I do, I just didn't think of it like that, I was just substituting it into the formula (I'll have to think more carefully next time). For the cosx=1, is it 2*k*pi from the formula?
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Oh yes, I meant there is a similar case for sinx = 0.
(Try and see the cases using the Unit Circle, it helps a lot).
Last edited by kawaiipotato; 21 Oct 2017 at 10:33 AM.
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Ok, so I think the simplified version for sinx=0 is x=pi/2 +2kpi, is that correct?
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Those two solution sets are the same (can you see why?).
Also, for finding the general solution for cos(x) (or other trig. functions) equal to some "special" values (basically 0 or ±1), it is usually easier to inspect the general solution from the graph rather using the general solution formula (the general solution formula will still give you the correct solution set, but it won't be in as "simplified" a form as it could be).
Last edited by InteGrand; 21 Oct 2017 at 11:47 AM.
Mathematics Extension 2 - Physics - Chemistry - Economics - English Advanced
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